There are 2 different meanings for hybrid mechanical:
1: A mechanical mod without 510-connector but has got a built in RDA/RBA/RTA/RDTA/some rebuildable
2. A normal mechanical but without a 'proper' topcap, meaning there is no adjustable 510 pin in the topcap, but it's just a threaded metal disc with 510 threads and the attys 510 positive post contacts the battery straight, which allows for a lower voltage drop and smaller mods