#40: Type 2 Indexes Can Impact Storage Requirements
A Type 2 leaf page has 4038 bytes of usable space; a Type 2 non-leaf page has 4046 bytes. Type 1 leaf and non-leaf pages have 4050 useable bytes per page.
So, Type 2 indexes have less usable space per page.
Type 2 indexes require an additional one-byte RID prefix in addition to the four-byte RID found in both Type 1 and Type 2 indexes. The new one-byte RID prefix found in a Type 2 index contains three flags: pseudo-deleted, possibly uncommitted, and RID hole follows.