[viraptor]

Heroku is a bit higher level. If you're using heroku, you're using their blocks and their methods of passing traffic, logging, etc. With lambda, it's just a function. You have to connect everything yourself, not you can do it exactly the way you want.

[gitgud]

You can redeploy a Heroku app to many other servers and platforms relatively easily.

However, I'm not sure you can do the same with AWS Lamda Functions. To mean, this means it is like a lock-in.

[viraptor]

It's just code with basic function entry point. You may get your parameters and configuration in a different way, but not much else changes. There are only so many ways to call some code.