It depends on the exact context, but:

“Trivial” usually means “not important.” For example, a person gets an echocardiogram and the cardiologist reports “trivial regurgitation,” it means the valve is leaking so little that it’s not worth worrying about.

“Naive” means not having experienced that thing. For example, in pain management, there is a distinction between “opioid naive” people, who have not previously had opioids, vs. “opioid tolerant” who have taken opioids long enough that the effects are lower on them. The tolerant group can take higher doses that might put the naive group at risk of death.

The way I understand it, trivial is something that takes little to no effort to accomplish; naive, without previous knowledge or without solid assumptions about a problem.

In maths "trivial" is usually when the author has a statement they could prove, but chose not to (either because is too obvious, stems from a result in another text, or is a lenghty proof)

Trivial solutions are often ones that don't provide any useful insights to explore. Not that they're not part of the solution space, or valid solutions, just that for the purposes of the lecture or paper which is likely to glean some deeper insights, that they are not worth explaining.

Often these are things like something moving with 0 velocity, you can trivially show conservation of momentum for example, or if a system is in equilibrium there are technically dynamics but there's not much about the rules of those dynamics that are illustrated in that system.

Naive in mathematics is usually a solution or attempt at a a solution that is the obvious one. Often times it's in the context of the naive solution being a slow or laborious baseline that can be contrasted with a more clever solution.

Also to note that there's a statistical term called Naive Bayes which basically has no assumptions to calculate some things. So basically no assumptions is the best definition