What's the difference between ”concrete“ and” specific“ ?

For instance：
There is a dialogue about concrete/specific issues and problems.

Thank you very much for reading

Question

What's the difference between ”concrete“ and” specific“ ?

For instance：
There is a dialogue about concrete/specific issues and problems.

Thank you very much for reading

Answer

In that sentence, "concrete issues" and "specific issues" are basically the same thing. People use the terms interchangeably most of the time.   That said, there is a difference. "Concrete" in this context means "not general or abstract." "Specific" can mean both "explicitly stated" and "limited or detailed."  For example:
General issue: transportation is a problem here
Concrete solution: build a road
Specific solution: build a road from this hill to that river
I hope that helps!