They are both the same thing.
TF or T-Flash is a abbreviation of "TransFlash".
TF was the original name given and started around 2004. SD is a abbreviation of Secure Digital. Micro SD card is the updated version adopted by the SD Card Association. (A group of Manufacturers).
You can use a TF card in a SD card slot and SD cards will work in TF slot.
Source.
https://en.m.wikipedia.org/wiki/...
