Why does backlink watch show backlinks then majestic doesn't show any?

This backlink stuff is confusing me now.

I understand if majestic shows MORE backlinks which is what I found when I 1st tried a link. backlinkwatch showed 31 while majestic showed 312 or so- 25 domain and 312 external- what do these figures mean?

So why does backlink watch show I have 12 backlinks to my web 2.0 while majestic says it doesn't have any?