An app won't be on sd unless you move it there, and even if you do it's moved to a special folder which is wiped by a factory reset.
But I noticed that all the apps I downloaded went straight to the SD card without giving me a choice to put it in internal storage. Also, on my phone (Coolpad Quattro) there is an option to do factory reset with or without
erasure of the SD card. It does say that factory reset alone will remove all applications. Although applications on the SD card are not mentioned separately, I am supposing that all means all. Including the SD card in the reset option means music/photos and other data files are also erased which would otherwise remain intact.
Please let me know if I have understood correctly.