OSPF - Normal, Stub, Totally Stub and NSSA Area Differences

ref.: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094aaa.shtml#definestub

Normal	None
Stub	No Type 5 AS-external LSA allowed
Totally Stub	No Type 3, 4 or 5 LSAs allowed except the default summary route
NSSA	No Type 5 AS-external LSAs allowed, but Type 7 LSAs that convert to Type 5 at the NSSA ABR can traverse
NSSA Totally Stub	No Type 3, 4 or 5 LSAs except the default summary route, but Type 7 LSAs that convert to Type 5 at the NSSA ABR are allowed

more information about LSA type:

http://raycheang.blogspot.com/2012/03/ospf-lsa-type.html