Is it unethical to submit for review multiple articles which overlap in some respect?
You should avoid self-plagiarism. Having an identical section in both papers would be ethically questionable. They could have the same overall meaning, but I would try to rephrase them differently as you might already have done.
Also have your papers cite each other as being submitted, and possibly update the final manuscript with full citations.
It may be a good idea to let the journal editor know that this is happening. They may be able to provide you with specific guidelines.