My external drive is running out and I do not want to reformat or move all of my itunes libiary but is it possible just to move the ios apps to a diffrent location?
You can also move your entire home folder, onto an external drive. I think that this option might be better off for you. If you go this route make sure that you read up about it first. There is an extra step you take in account settings.
If it were me I would just put all my music on an external USB drive.
Also note that whatever you put on a USB drive will run slower. If it is apps they will start up slower. Music and data are best.