Do-follow & No follow are the biggest question that most people be confuse or ask in community. So let me tell, Do-follow links are those links which Google follow or give value & another side No follow links are the links those Google don't follow or don't give value.
This is the simple different between Do-follow & No follow links. Now let's talk about "Advantage and Disadvantage"
Advantages of Dofollow :-
Dofollow blogs attract visitors
Get huge traffic
Google give authority
Disadvantages of Dofollow Blogs
Lots of spammy comments
It takes lot of time to moderate to approve do follow link.
Advantages of Nofollow Blogs
Spammers can't spam your blog
less time to moderate comments
Disadvantages of Nofollow Blogs :-
Less amount of comments