[Hippocrates]

I think the problem with these two roles is actually the confusion about what each is. Usually the issue is a "product" manager not doing the ideating, not doing research, not enough advocating about what user needs or what the product should be. Instead they do too much "project" management which amounts to gantt charts, check-ins, and nagging about status.

I have seen that in all sizes and maturities of company that people view these roles as interchangeable and they are not.