Available apps on Nexus vs S7 Edge

Available apps on Nexus vs S7 Edge

At the end of my contract with verizon, im jumping ship to Google fi. Ive done extensive reaserch on the web, and found no real negatives. Especially, where I live and work in areas that all 3 fi carriers are strong. My question now is about nexus phones. Im a longtime galaxy owner with an S7 edge. I know I'll be diwngrading a bit. My question is, will I be able to use all my apps that I git ftom google play store? Exactly what is straight android?