When you press edit on a transaction you can choose an image, but when you press view, you can select attachments. What is the difference other than i can only choose one image at the edit screen?
The images you include in the edit screen are not real attachments. They help some when looking at the Tab-list to be certain what it was about. The attachments to the view screen are not restricted to an image, but can be documents, spreadsheets, etc as well. You can also add more. These are in support of what ever your view screen show. If it is for payments, you could for example attach a contract (PDF) and an image of a signing ceremony. They add to that payment information.
We do not use the images upload in the Edit screen as its use for us is very limited compared to what we can do with the attachments to the view screen. The view screen attachments exist much longer, while the images in edit screen were implemented much later and have weakness in that you can bulk delete them but have to go one by one editing each transaction, item etc and press on the trashcan within the area where the image was uploaded.