I got stuck on tutorial

[Fonte Boa]

However today as I was trying to follow next steps in this tutorial, I had problems with using 'mirror' tool. I noticed that when I used this tool from RMB faces edit menu, the mirrored part was created but it wasn't actually a mirror. I mean, it looked as it should be (exactly the same) but when I was trying to select something on the original part, the selection wasn't transferred to the newly created (mirrored) part. But when I used 'virtual mirror' from the tools menu - it worked OK. Could you please explain it to me - what is the difference between those two options?

I think i've already found the answer!

Face|Mirror command just mirror the object around the selected faces.
(ever keep your attention in Info Line when your cursor are over a command: in this case, there is a difference between click with left or right mouse buttons - you can read the instructions there).

Tools|Virtual Mirror|Create command creates a virtual mirror "condition", ie, everything you do is duplicated at both sides of objects, better saying, at both sides of virtual mirror plane (until you call Tools|Virtual Mirror|Freeze, when you finished that "virtual mirror session").