I have both, and they function pretty much identically. Nano programmes keys with the short code on the back of the circuit board (but there is a Google spreadsheet that generates the long form), and it handles programming the air bag heights better.
The biggest difference though is the screen. The Nano has a big touchscreen, so you can see more live information at the same time (useful for diagnostics), whereas the Hawkeye has a small three or four line display and physical buttons. If I were running a garage, I'd have the Hawkeye as it is more robust IMO. As an enthusiast, the Nano is better.