4L80E is based on the TH400 with an over-running clutch, an overdrive clutch, and an overdrive gearset added. It is beefier and bulkier than the 4L60E, requires a TH400 style driveshaft yoke, and slightly different shift solenoid operation than the 4L60E.
The 4L60E is i deed based on the TH700R4 with electronic controls added.