You are comparing one very old compiler with another very old compiler. A somewhat pointless exercise.
As for compatibility of actual code, that depends. Some aspects of the language have remained unchanged for years, while others have moved forward. There may also be some proprietary or non-standard code written with older compilers.
Broadly speaking, the answer is the same, use the most up-to-date compiler that you can get access to, and if necessary update your existing code to meet modern standards, to enable it to compile.
By the way, the latest version is 5.3 (Orwell Dev-C++).
Or use Visual C++ which is usually recommended.
If you need help in fixing code incompatibilities, then give details of the problem, someone should be able to help.