Electron Proton Collisions and Electron Capture

[nokia8650]

What is the difference between electron capture, and electron-proton collions?

My textbook has the feynman diagram of electron capture as a proton decaying into a neutron, and the proton emmiting a W+ boson, which is received by an electron, which then decays into a neutrino.

However, the electron proton collision has an electron decaying into a neutrino and the electron emitting a W- boson, which the proton recieves, which decays into a neutron.

Obviously, rather than proton and neutron, up and down quarks can be used in the above.

Why is there this difference in the two processes?

Thanks

 

[blochwave]

That's a helluva intro physics class, eh? :)

Seeing as how I hate particle physics, my answer is probably a bit biased, but I would assume the reason is because IT'S ALL A BUNCH OF BS >_>

seriously though, I know electron capture is an event that takes place in the nuclei of atoms, so I would wager the electron-proton collision is a similar event that takes place outside the nucleus. Assuming there IS a difference besides the very fundamental one you described