Original post by Mjr_issuesWell, why have you chosen one over the other? Did it just feel like you wanted to go diagnostic? Here's a quick and likely flawed and biased outline so you can come up with some reasons.
Therapy radiography tends to focus on treatment of cancer and other diseases over a period of time with the same patients. You build up a great relationship with your patient over the sessions, which some might like, others might not. You get to know some patients will make it and be better off, but sometimes it's palliative more than radical, which I imagine can hit some people hard.
Diagnostic radiography tends to be quick contact with patients - you see them, have to build up a relationship very quickly, and then image them. You need to be able to "snap" to the patient and ensure they trust you - adapting to different patients is key. You'll deal with a lot of folks from all walks of life and see a lot of variety. You'll also see a lot more variety in your imaging methods - I believe therapy use the CT scanner to target treatment, but diagnostic uses a whole lot more - conventional radiography, fluoroscopy, CT, MRI, ultrasound and so on. You'll also work with a lot of hospital staff - diagnostic can be in A&E, in the general department or on the mobile scanners if the patient is in too poor condition to be brought to the room.