Super Sentai is known to have diverse team-members for each season. Usually, if the team has two girls, they are polar opposites. And sometimes, that leads to conflict. And that leads to a great episode.
Here are the differences between each girl.
Mika and Hikaru in Bioman
Mika was more tomboyish than Hikaru, and Hikaru was more girly. Also, Mika wasn't as obedient as Hikaru.
Jun and Hikaru in Bioman
Jun was more athletic than Hikaru, and more tomboyish as well.
Sayaka and Mai in Changeman
Sayaka was more strategic and thought before she acted. As well, she was more girly and had manners. Mai was a tomboy who was more reckless, and didn't care so much about acting ladylike.
Sara and Lou in Flashman
This was the first series to not have the tomboy vs girly-girl difference. Albeit both acted masculine and feminine. Sara may have worn a short skirt, and spun around in the theme song, And Lou might have done a don't you mess with me pose in the theme song, but she had girly moments as well. You couldn't really show Sara's ability in the theme song. Sara's helmet isn't as feminine as Lou's heart shaped visor.Sara's weapons are gender neutral (shocking beads out of suit, batons when transformed) whereas Lou's weapons are pretty girly (shocking hearts out of suit, boots when transformed). The main difference is that Sara is more strategic, and slightly more intelligent, and doesn't let go of her emotions, and her cold demeanor is scary. Lou can be scary too, because expresses herself more, and can get angered more (I think). Lou was in more feminine situations. She became a surrogate mother to a Beast Warrior in one episode, and she cooked for the team in another. I think both were meant to be raised genderless in the Flash System. Lastly, they both discovered what love was at different times. Lou discovered it earlier in the series with the Beast Warrior mother episode, and Sara later in the series.
Haruka and Momoko in Maskman
Both of the characters weren't developed as much, due to the fact Maskman mainly focused on Takeru. Haruka was very man-like, intelligent, and fierce. Momoko was more gentle, girly, and romantic. This was evident in their differences in their martial art forms. Haruka's a ninja, and Momoko's a tai chi practioner. Both are extremely different forms.
Kazumi and Remi in Fiveman
Kazumi was more maternal, and slightly girlier, whereas Remi didn't like doing housework, and was slightly less girlier, slightly.
Kaori and Ako in Jetman
Pretty simple. Kaori was rich, feminine, and polite. Ako was boyish, of normal income, and wasn't as polite. Also, Kaori was more lucky in love, whereas Ako didn't really get that much attention, and if she did, it was from a ramen-obsessed stalker, and an awkward bird-human who lift up her skirt.
Juri and Momo in Ohranger
Juri originally started out as tougher than Momo, and Momo was gentler and girlier. But that changed as the series progressed.
Natsumi and Youko in Carranger
Natsumi was the intelligent mechanic, and very serious about her duty as a Carranger, and she was very masculine. Youko was ditzy, yet somehow good at accounting, feminine, and ate a lot. Also, Natsumi dressed very mannish, and barely showed off her body, whereas Youko dressed flirtier.
Chisato and Miku in Megaranger
Chisato was more organized and a better student, and slightly more intelligent. Miku was hyper, ditsy, and didn't really care about school, but she did show some moments of genius. They both were creative, and sang.
Jasmine and Umeko in Dekaranger
Jasmine was more composed, sultry, and intelligent. Umeko was hyper, somewhat ditzy and reckless, and was more flirtatious.
Houka and Urara in Magiranger
Houka was extroverted and was a total flirt. Urara was terribly shy, yet was more monogamous. She was ready to settle down with one person, than date a bunch of other men.
Natsuki and Sakura in Boukenger
Natsuki was ditzy, hyper, and naive. Sakura was mature, intelligent, collected, and more responsible. Sakura was also vied more by the male members of the team. No one was really attracted to Natsuki.
Saki and Miu in Go-Onger
Miu was richer than Saki. Saki was more optimistic than Miu. They both were girly, although Miu was more composed.
Mako and Kotoha in Shinkenger
Both were equally strong fighters. Mako treated the whole team like her children and was very motherly in her interactions with them. Kotoha was very shy with the team, and was worried about being awkward when she interacted with them, and was afraid to speak up. Mako wanted a normal life, and her dream is to be a wife and mother. Kotoha truly feels at home as a samurai, however. Mako was less traditional and referred to Takeru as his first name. But she treated him like a little brother or son more than anything else (which a lot of the fans thought of as a ship tease, despite that. Next time, really watch the show). Kotoha treated Takeru with humility and referred to him as tono-sama. She admired him dearly, though, and developed a crush on him. This modesty and humility was something Takeru wanted to break. Mako was able to get under Takeru's skin, and give him a motherly talking-to, but Kotoha was able to break his facade and make him smile or blush. Finally, Mako has a legion of fanboys in real life, and is really over-rated by them. Kotoha is under-rated, and doesn't have as much fans. People say that she is weaker than Mako and underdeveloped as character despite that not being the case.
Eri and Moune in Goseiger
Eri is slightly girlier and well airy. Moune is stricter, organized, and down-to-earth. Both can act immature.
Luka and Ahim in Gokaiger
Luka was ridicously poor, whereas Ahim was ridiculously rich before joining the team. Luka's manlike, yet can be flirty, whereas Ahim is demure and extremely feminine. Luka has street smarts, whereas Ahim is not used to living like this, and can be too trusting, but despite growing up rich and sheltered, she is not spoiled. Luka cares more about treasure, whereas Ahim wants to save people. Luka is more straightford, while Ahim can get anything from anyone by being sweet and princess-like. Also, fans seem to like Luka more, but Ahim deserves as much praise as Luka for being a princess who lost everything, and didn't act like a spoiled little brat because of it. Can you imagine what would happen if Paris Hilton was bankrupt? Actually, remembered that show, The Simple Life. That is the opposite of how Ahim acts.