VSTO add-ins vs web add-ins vs add-ins created by javascript API for office (1 Viewer)

What's the Difference?

And also Please confirm whether the "Web Add-ins" and the add-ins created by the Javascript API for Office is same?

Is it possible to create a JavaScript API addin using the Visual Studio? (New Project->Templates->Visual Basic->Office/SharePoint->Web Add-ins)

Are both same?

I want to extend my knowledge beyond the VSTO add-ins(Document and Application level add-ins). Which is the right book to start? Thank You!

P.S:
If possible please explain what is office.js

if you just copy your thread header into google you will find plenty of hits on the subject. Same for your question on office.js