Full logs EVERYTHING as it happens.
Bulk-logged reduced logging for some operations such as bcp, CREATE INDEX, SELECT INTO (see BOL for full list) as theyhappen. Bulk operations are then fully recorded at the next T-log backup.
This means you can do "point in time" restores in Full because all restore info is available in order etc.
In Bulklogged where you restore only to the last T-log backup (to redo the bulk operation)
HTH, Shawn