Comparison between strings
There is a subtle difference between == and CompareTo: the latter is current-culture-aware (or you can pass another one in), the former is not.

However, as Ben points out in the comments, the official recommendation is to use Equals instead of CompareTo outside of sorting operations.

Your devs might also be coming from a Java background where == and equals are a bit more complicated and may very well produce different results. This isn't a concern in C#, so for the vast, vast majority of your equality checks the == will be more than sufficient.