Diffent voltage on each side of bus bar
Classic "lost neutral"

They are different, but add up to around 240v... That is the classic symptom of a loose or open neutral in your cable or more likely, its terminations.  

Hot to hot, the voltage is 240V.  You have two sides of 120V with neutral in the middle.  If the neutral is working, it forces each side to 120V.  If the neutral is lost, then the two sides are simply in series, and they will add to "whatever" based on the loading on each side.  

This can be quite destructive to equipment and even start a fire.   I would shut off everything (240V-only loads are OK) until you can fix it. 

Also, if one terminal is failing, possibly others are too.  When you find the problem, check the two hots and ground also. 

Or it could be no neutral

In older installations, we sometimes see really dumb setups like 2-wire 120V circuits converted to 240V by trying to use the local ground rod as the neutral.  This doesn't work. Dirt doesn't conduct electricity very well. It can't function as a "current return".  This acts like a "lost neutral", energizing the neutral and the ground to hazardous voltages. Not good.  In this case, it might have been like this all along and you only just noticed, or soil conditions changed where it's not returning as well as it used to. 

This entire type of setup needs to be taken out of service ASAP.  Convert it to 120V only, convert it to 240V-only (no neutral in use - easier than ever now that many lights are 120/240/277), or use a transformer to convert it into its own main service.