[nabla9]

JWST and Hubble have roughly similar angular resolution. Hubble marginally better. JWST needs larger mirror for the same angular resolution because it uses longer wavelengths.

  Hubble: 0.04  arcsec at 500 nm 
  JWST:   0.068 arcsec at 2 μm

The difference is in wavelengths, image quality, and light collecting ability (size of the mirror). Hubble has to stare longer into a same spot to collect the same amount of light as JWST.

(If I remember correctly JWST took this image in less than 12 hours, Hubble stared at it for much longer. Correct me if I'm wrong).

[0x_rs]

Hubble's composite of SMACS took 5 orbits, which ends up being about a couple hours maximum. Most websites talked about the deep fields such as XDF (hundreds of orbits) while showing the comparison between the RELICS and JWST pictures, which I believe was very misleading from how this is repeated. Not to detract from its capabilities, of course.

[sph]

Would JWST have made a more detailed picture if it had stared on that spot as long as Hubble did?

[gliptic]

Resolution would not improve, but contrast would and you would be able to see fainter objects with less noise.

[Synaesthesia]

The longer you "expose" the more detail is revealed yes.