What are these fish

I my gf got me 4 fish for christmas but i dunno what they are and i dont think she does ither.

there are two dark orange with black tips on their tail about an inch and a half.
i tryed to get a pic but their camera shy.
http://i48.tinypic.com/2mpzi93.jpg

and there are two silver ones with a bit of orange also about an inch and a half.
http://i46.tinypic.com/2ro426v.jpg

Both of them:
http://i46.tinypic.com/2cxw5u8.jpg

They all came from the same tank in the shop so i think two are girls and two are boys but i dunno. If they are what sort of things should i know about breeding.

I also have a plant in the tank that i dunno what it is but there is pleanty of light so it should be allright but heres a picture of it anyway its about 5 inchs tall
http://i47.tinypic.com/2py5pi1.jpg

Looking around on the net im pritty sure the two orange ones are a male and female Swordtail the male seems to have a point at the bottom of his tail that you cant see in the pictures the other orange one thats not in the picture doesnt have this so i think its a girl. the other two look quite like platys but they look a thiner and longer. yea Stargazer53 got it right looks like a Pineapple Swordtail thanks for the help.