[ffhhj]

Comparing both images, there is a perfectly round red dot that's just a few pixels wide, a little up from the most prominent star, which doesn't correspond to another object in Hubble's image. Is that an image artifact or some laser guide?

[sbierwagen]

Could be an internal reflection. The optical path for many JWST instruments is, uh, compact: https://www.esa.int/ESA_Multimedia/Videos/2021/09/Webb_MIRI_... (Every kilo on telescope structure you save by folding the optical path is a kilo you can add in propellant, extending the working life of the spacecraft)

Instrument internals are painted black and heavily baffled, but nothing in optics is perfect. Dithering the direction the telescope is pointed in and image stacking should cancel out most optical artifacts, but internal reflections will be worse for bright objects like stars, which JWST probably isn't usually going to be observing with the imaging instruments.

[jccooper]

It is a bit suspicious looking, but there's a lot of very red objects that the Hubble image doesn't catch. Presuming that the red colors in the images are the deeper infrared wavelengths (and thus the most heavily-redshifted objects) I would guess that Hubble just didn't have the detectors to see those.