Question

What’s the difference between, _context.SaveChanges and _context.AcceptAllChanges(), is the AcceptAllChanges() is sort of reloading data from Database or rolling back (discarding) changes made by the user when he didn’t use SaveChanges()

Answer 1

ObjectContext.AcceptAllChanges Method – MSDN

If the SaveChanges method was called and the AcceptAllChangesAfterSave
was not specified, the user must call the AcceptAllChanges method. The
AcceptAllChanges method is useful in the scenario where a transaction
has failed and a user wants to retry.

You may see this: http://blogs.msdn.com/b/alexj/archive/2009/01/11/savechanges-false.aspx

If you call SaveChanges() or SaveChanges(true),the EF simply assumes
that if its work completes okay, everything is okay, so it will
discard the changes it has been tracking, and wait for new changes.

Unfortunately though if something goes wrong somewhere else in the
transaction, because the EF discarded the changes it was tracking, we
can’t recover.

This is where SaveChanges(false) and AcceptAllChanges() come in.

SaveChanges(false) tells the EF to execute the necessary database
commands, but hold on to the changes, so they can be replayed if
necessary.

Now if the broader transaction fails you can retry the EF specific
bits, with another call to SaveChanges(false). Alternatively you can
walk through the state-manager to log what failed.

Once the broader transaction succeeds, you simply call
AcceptAllChanges() manually, and the changes that were being tracked
are discarded.