Both white and dalmatian are females. Is the left most picture the dalmatian one in the second picture? I'm only asking because in the first picture it's definitely a female, but in the second one the anal fin shape is a bit harder to distinguish.
It is easy to tell tropigod. The female has an anal fin, the one next to where they eliminate, that is a fan or triangle shape. The male's anal fin is modified to be basically a line shape and is used to impregnate the female. I don't have a clear picture of a male molly but this pair of pictures of a similar fish will let you see the difference.
Male
Female
The pictures are a bit grainy because the fish themselves are very small. They have a reputation for being the smallest livebearers of all but I don't know if that is true. As adults they are about 3/4 inch long for the male and about an inch for the female.