Equal Protection in the election lawsuits

Here is the decision from the Middle District of Pennsylvania that everyone has been talking about. The introduction is pp. 1-11 and the equal protection analysis begins on p.23 (in between is a discussion of standing, which you can ignore for our purpose). Note 1) how the court describes what is necessary under the equal protection--the problem is not classification but treating similarly situated persons differently; 2) the discussion of leveling-up and leveling down for equal protection remedies; and 3) the question of standard of scrutiny in election cases (which we will discuss on Monday).

Note, as well, the difference. between a substantive due process violation and an equal protection violation. SDP argues that government cannot do something or stop me from doing something; EP argues that in doing something that it might otherwise be able to do, government is treating me differently. This is why Holmes described it as a last resort. So in this case: A due process claim is that election officials prevented observers from being close enough to observe. An equal protection claim is that there is no right to observe, but officials let Biden observers closer than Trump observers.

On that note: What is the difference between a claim for a violation of fundamental right and a claim for an equal protection violation touching on a fundamental right?