The ECO is an Officer-sized 1911. It has a 3.5" barrel, with a compact frame. It is very concealable, but not nearly as small as a P938. The P938 is a pocket gun, the ECO is not. It is lightweight, but not as small, light, or concealable as the 938. It will, however, be much easier for most to shoot, especially with follow-up shots, when compared to the much smaller P938.
I've had two in 9mm, and one in 45. Loved them all, and still have one in 9mm. The others were only sold for other "must haves".
Good luck!