In our books, the following distinctions apply:

Gen1 = Bitcoin and forks
Gen2 = Decentralized Asset Exchange, extended functionality such as phased transactions or smart contracts: NXT, Ethereum, Waves. Still generally uses the same full blockchain structure as Gen1

Gen3 = Gen2 features, perhaps expanded, but the main groundbreaking improvement over Gen2 comes from restructuring blockchain and / or distribution mechanism, or other major area not limited to upper level features as such. For HEAT, these main distinctive characteristic are based on Proof-of-Presence distribution mechanism, sliced blockchain, and high scalability.