Ok, so to put rest the debate on the New Bosses vs Regular NPCs of the same name - the following pics show the difference...
First the Lowest of the Low... the Gravedigger... at L2 we kill them pretty easy at only 75HP - but - his Boss is 675HP... to a player at only L6 (usually when you go playing in the Woods) - thats a really big number to survive yourself...
For a Medium Subject - a Birgade... nice shot here as I was able to attune them both - one showing 1450HP - his boss at 3100HP... once again, at L15 the player would be beat down taking on this guy alone...
Finally - the stronges Boss I found so far... a Raider Boss... a normal Raider is around 2650 but our Boss... over 5900... at L30... a player taking this guy on would lose for sure (or be praying to use a lot of tonics...)
So even though a L40 Player could probably take these guys on and survive - if a player at their initial contact level with the boss enemy tried to take on one of the bosses of the same name - they would be in some trouble