If you squish an electron and proton really hard, you'll get a neutron [1].
[1] https://en.wikipedia.org/wiki/Electron_degeneracy_pressure
Strong-force-wise, they are very hard to tell apart.
Weak-force-wise, you have the obvious changes in allowed interactions, but it's all stuff that's plain once you understand the theory of the weak force. No surprises.
Electromagnetism is actually the interesting one: just how neutral is this neutral garbage can? There are some interesting measurements to be made here. ILL in particular has done a lot with neutrons.
And the there's gravity. Gravity, you ask? Really? Yeah! If neutrons are really neutral, they don't interact electromagnetically, it's hard to get the strong force to come out and play, and the weak force only really does its thing here on the predictable* timescales of neutron decay... so all that's left is gravity. And thus, neutrons get used (or, I guess, more commonly just proposed...) as probes for gravitational effects! Fun, huh?
(* Mostly. See neutron lifetime controversy....)