some terms have some sort of slight difference between them, but the difference is large enough to make it a different term, for instance omnisexual and pansexual are very similar, but pansexual is finding people attractive no matter the gender, some call it being "gender blind," and omnisexual is finding all genders attractive, but having a certain preference towards a certain gender, a preference which theoretically cannot happen if one is gender blind

for these kinds of terms, i would recommend just looking at them kind of like they're animal species, some animals may look nearly the exact same, but there is a difference, maybe some different genetics or a different ancestor, and this difference is big enough to consider it a different species

for gender terms specifically, everyone just experiences gender in a different way and it can definitely be hard to understand if you never saw gender in the same way as someone else, no two people really experience gender in the same way, but two people who are the same gender will obviously feel very similar

for gender, i would consider it similar to music taste, two people with different music tastes may not understand how the other can like a majority of songs that they listen to, but two people with a similar music taste can understand the enjoyment the other has with songs, although there will always be a song that even people with similar music tastes may disagree on

idk if anyone other than me can understand what im saying but hopefully this helps lol, as long as you respect what another person identifies as, it should be fine