It´s platy variatus (longer form, probably hybrid with swordtail). The platy maculatus is the rounder one, with a shorter body. They come in many color variations (hence the name) in wild and captive form. They hybridize readily with both swordtails and regular platys. It is a male.
The way you tell is to look for a long narrow anal fin called the gonopodium. The males use this fin to deliver sperm to the female when spawning. Females don't have this fin and their anal fins are all rounded.
The one in the top of your photo is a male, but I can't see the other one's fins well enough to tell if it has a gonopodium or not?