Can i put an Android Sim Card Into an iPhone?

Alright so I have an LG G2 and it's been going really slow and just gets annoying… I wanna get an iPhone 6 off eBay, but I'm afraid that I'm not gonna be able to just put this sim card into that phone. I have a 2year contract but it ends next year… What should I do because I really want an iphone 6

Your carrier won't care if you replace the phone. You will have to pay full price for the iPhone.
If the SIM card isn't the same size, your carrier will give you a free SIM card if you go to one of their corporate stores. Retailers will sell you a SIM card for $5-25. Or you can buy a sim adapter kit online for about $3-6.

There are no special Android or iPhone SIMs. As long as the iPhone is either unlocked or locked to your carrier, it would work.