I have both (and a 642 as well) and would say that the J-frame conceals quite a bit better than the baby Glock. It's also a lot lighter. Its shapes are more rounded and hide better than the blocky Glock. Also, you'll have the option of pocket carry should you need it. The only concealment drawback is that speedloaders are bulkier and more awkward to carry than even double-stack Glock magazines, IMO.
Unrelated to concealment, the Glock obviously wins the firepower/capacity contest.
In daily life, I pick a J-frame (or two) over the Glock practically every day.
Best regards