The Key Difference With The Hubble Telescope.

Being that the Hubble Telescope sees, mainly, the Visible Light part of the Electromagnetic Spectrum.

While the James Webb Telescope sees, mainly, the Infra-Red part of the Electromagnetic Spectrum.

http://www.xinhuanet.com/english/northamerica/20220125/6ae6e660d138461db635b6e964fa5a55/c.html

Allowing it to see further into distance/time.