@r6155 in Table 17-4 butt weld Details 1.1 to 1.3 ; 1.5 and 1.6, it is a classical BW with pipe to pipe joint. Now think that the pipe on the left side is not hollow, but it is a full cylinder instead, and you have the exact same drawing of the first poster. Which is attaching at tubesheet to the shell. I understand what you say, it is a full penetration welding and it is not a pipe to pipe joint, but for some welding standards it is called a butt weld BW (in AWS they call it groove weld GW instead) to differentiate it from fillet weld FW.
In figure ASME VIII DIV. 1 Figure UW-13.2 the first poster drawing correspond to (c) or (d) and it is a typical way to attach the tubesheet to the shell welding from external side only.
The general nomenclature of welding in regards to EN 13445 is in EN 1445-5 figure 6.6.2-3 "type of weld" and table 6.6.2-1 at column "type of weld". What is asking for the first poster is in regard to rows 9, 10, 11 "Assembly of a flat head or a tubesheet, with a cylindrical shell".
Look at ISO 9692-1 (Welding and allied processes — Types of joint preparation) they divide all type of welding ends in 2 main types BW or FW. The same goes with ISO 9606-1 and many other related standards which are then more important for qualifiaction of WPS.