Merkur Razors by their heads

[Galhatz]

I am trying to figure out the differences between the models.
The obvious is the handle, the less so is the head design.

Except for the adjustable razors, what head designs are shared across models?
Meaning:
Classic CC head: 23C, 33C... is the HD part of this group?
Classic OC head: 1904/41, 25C - BTW: is it the same head as the Muhle R41 ?
Slant - 39C 37C

Let's complete the list

 

[AABCDS]

All the Merkur safety bar razors have the same head. The same goes with the open comb heads. The Muhle 2009 R41 uses the Merkur open comb head. The Muhle 2011 R41 does not use the Merkur open comb head.

 

[Galhatz]

Thank you for clarifying this.

 

[nemo]

All the Merkur safety bar razors have the same head.

Not quite. You can't really share the heads of the "two-piece" HD style and the three-piece, that's for sure, but the geometry is the same.