I think the “famous” ‘Simple Made Easy’ talk makes this difference you mean quite palpable: simple is an objective term meaning something is not “interconnected” (not complected) with other parts of the code, while easy is a relative term originating from something being close to us, it being familiar.

So to most programmers, imperative code is easy and FP is hard, but on an objective basis both can be simple. In a way FP may be simpler (according to the talk), as e.g. mutable variables complect/mix together values and time.