Okay, here I go yet
again -- but I just have to ask: Butt chisel vs. bevel edge chisel
-- how are they defined and what's the difference? Mortise chisel
vs. sash (?) chisel -- again, how are they defined and what's the
difference?
That’s OK… some of it
still confuses me these days as there is some overlap between types.
This is just my take on it as terminology by trade and era varies a
bit:
Bevel edge doesn't mean
much per se, as even some firmer and framing chisels have them... it
merely allows getting into a tighter corner.
Neither does
socket or tang handles, although the larger chisels are generally
socket chisels, as are many high-grade chisels, as sockets are
considered a better design as handles are easier to replace, but
cost significantly more to manufacture.
To call a chisel a
“socket” chisel with no other descriptor is a common mistake today,
often by people who should know better.
Butt Chisel
Any short chisel, usually
with bevel edge and design suitable for paring and striking with
30-degree bevels. A finish carpenter or shipwright’s pocket
chisel easy to store with a major role in hanging doors and all
around trimming. Usually tang handles.

Bench Chisel
Longer chisel for
workbench use. Paring and light chopping, usually with 30-degree
bevels and beveled edges.

Paring Chisel
Long, thinner chisels not
designed for any striking, only paring with 20-25 degree bevels.
Some have "cranked" handles for clearance and were primarily used by
pattern makers making negative patterns in soft pine.
Others
are skew cut to reach into corners, and a “dovetail” chisel is
diamond-shaped to clean female sliding dovetail sockets.
Usually with tang handles.

