I'm doing both (engineer as job, flying as hobby). I think being engineer needs more knowledge than being pilot, as piloting is somewhat repetitive. You're doing the same actions and checklist over again. Base maintenance is about the same. Line maintenance however can be unpredictive, as any system can go wrong, and you need to solve it in time.
However, flying an airplane with big problems also needs skill.
To put it together, engineers and pilots all need to have quality and responsability in their job. The paytrates are not the same, but then again, pilots pay more to have the license in the first place.