Hi Dave,
Nice finds!
I hadn't seen this question yet (so it's good you bumped it

) but the answer is pretty simple: the cases are just about identical, except for the neck crimp. The Type 11-Year Infantry gun calibre does not have a neck crimp, whereas the Ho-203 variant does have a deep neck crimp. Your images shows that you have both kinds, with the complete round being a proper Ho-203 specimen, with the correct projectile. The Type 11-Year rounds used the regular kinds of projectiles that were also used on e.g. the 37x132R and 37x165R calibres (as well as the more exotic 37x250R types). The Ho-203 HE projectile is distinctively shorter.
Incidentally, both your casings are from 1943; this was to be expected from the Ho-203 one, but is slightly late (though not unseen) for the Type 11-Year one, which was first introduced in Taisho 11 (= 1922).
In somewhat more detail, both casings were made by the Nagoya arsenal, the Type 11-Year one in July 1943 (the primer was manufactured by the Osaka arsenal in April, 1943), and the Ho-203 one in August 1943 (the primer was manufactured by the Osaka arsenal in July, 1940).
The references to the neck height will most likely refer back to either of the following two pieces of information you'll have read:
1) Ken Elks' section about the 'Sogekiho'; which is very close to the Type 11-Year calibre, or:
2) Possibly some comments/questions from Robert Melichamp, who's looking into Chinese casings in 37x111R calibre having a longer neck.
Cheers,
Olafo