The girls are pretty epic and noticably more aggressive and less of a sweet talk among each other than in the game.
My guess that it was their true personality as they are battle/warrior type trope.
Also starlight are meant to be different from other girl game like love live! where they are more seem as competitive and willing to fight for each other to get to the top
And thats what the manga is about well not completely.
OK the story is about these girls and then we got a brief introduction of each other,their motivation of joining starlight etc..
Then we get to see their teachers and one of them is even more fierce and ruthless with showing the girls to get what they want from the stage.
each of them get 1v1 with any member then we get to see how their conversation or relationship is played out with specific member.
There is a feeling of regressed feeling with the member and each time they fight ,it show off more of their true colour and frivolous personality. All of them certainly want something from the stage and that to be selfish to stole one another brillance to make it at the top.
Anyway,thats all for the spoiler lol there are more things in the manga but i dont want to spoil any more so there u have it.
P.S also for another stage girls called Aijo Karen,she is just like any generic protagonist but there something i side with her in the manga about unity with other girls about stealing other spotlight and this also reflect on the plot itself
But thats just something i noticed and like a little more.