What's the difference between Job Title and employer relationship description?
Afaik, there is connection between the "Current Employer" field and the "Job Title" field.

If you select a contact in the "Current Employer" Field it will also create a relationship AND disable an existing "employer relationship" which is marked as "current employer".

If you create a "employer relationship" you will have a little checkbox that says "current employer". If you tick it, it will also fill the "Current Employer" field and uncheck "current employer" with the existing "employer relationship" (but not disable it).

By the way, if you share an address you also have the option to "Set this organization as current employer" - which effects I do not know from the top of my head.

All this "UI magic" has been introduced / revised a while ago and has confused me plenty. It can also be quite complicated when you try to use the API (e.g. for imports) as the "current employer" attribute is not availbale there (at least to my limited knowledge).

Hope this helps a little bit.