It seems both of the previous answers addressed the increase in total votes and total percentage, but did not answer the original question about the vote difference between Trump and his opponent in the two elections.
The original question asked to verify that in "every state that Biden won, there was a larger difference in people voting for Biden and Trump than Clinton and Trump." and later clarified "was BIDEN - TRUMP greater than CLINTON - TRUMP in each state carried by Biden?"
I just copied the vote totals as listed today on Wikipedia for the 2016 and 2020 elections into a spreadsheet and calculated the "D Vote - R Vote".
The claim appears to be true. In only 12 states + NE-3 district, did Trump's total vote margin over his opponent increase: Fla.,
S.D. All of those went for Trump (indicated by N/A in the "Satisfied" column, as these are not relevant to the tweet.)
In the remaining states and districts, Biden's margin over (or under) Trump (in raw votes) exceeded Clinton's margin over (or under) Trump: N.D.,
Calif. This includes all the states Biden one (marked TRUE and a reduced margin of victory for Trump (marked N/A).