The states which will have different electoral maps in 2020 than they did in 2016 are North Carolina and Pennsylvania. In North Carolina, this is thanks to the 2017 Supreme Court decision which found that the gerrymander violated equal protection. In Pennsylvania, this is as a result of a 2018 ruling by the Pennsylvania Supreme Court, later upheld by the Supreme Court.
Below is a map I've cobbled together from the 2016 and 2020 election maps from Wikipedia. The lines in blue are from 2016, and the lines in red are the districts for use in 2020, allowing us to clearly see any changes.
Adapted from Kurykh, Mr. Matté / CC BY-SA & Kingofthedead / Public domain
To go through the other states which have been mentioned; these were fairly doomed after the July 2019 decision on Maryland's gerrymandered districts. From page 30 of the ruling:
We conclude that partisan gerrymandering claims present political
questions beyond the reach of the federal courts. Federal judges have
no license to reallocate political power between the two major
political parties, with no plausible grant of authority in the
Constitution, and no legal standards to limit and direct their
Subsequently, the Supreme Court ruled that Michigan's 2016 congressional districts were to be used in the 2020 election, and similarly, Ohio's.