Cute! And I would definitely say female for both of them; because they're dark you can't see ovaries directly, but the shape of them is pretty obvious in their stocky bodies. The blue one on left is probably a delta tail- her tail's rays branch into sets of four, which means she isn't a veiltail (VTs only split into two), and having only four branches means she probably doesn't get enough spread to be considered a halfmoon. The one on the right might be a halfmoon or delta, depending on how wide her tail goes when she flares.
"Flaring" is what we call it when a betta sees another betta, their reflection, a finger, pen cap, etc. and puffs themselves out to look big and impressive. Their gills expand into a "beard" and their fins- particularly their tail- expands into a stiffer, fuller shape then what they look like when relaxed. It's useful for determining what tail type they are, since the only difference between a delta and a halfmoon or over-halfmoon is how far their tail spreads out when flaring.
Here's a pic I grabbed off Google of a female betta flaring.
See how much wider her tail looks than your bettas? That's because she's flaring. And because her tail doesn't form a perfect "D" shape but is more of a wedge-shape, she'd be a delta tail.
Last edited by Rana; 03-20-2019 at 12:59 PM.