I am hoping I can resolve this quick query I have.
Is there any difference transferring a photo from a USB cable from a camera and or transferring from insertion of memory card in PC?
[any difference in picture quality that is]
I know this is kind of a weird question, but I really do hope you can clarify this for me!
There shouldn't be any difference in the quality of the images no matter whether you connect the camera directly or use a card reader.
There is no quality difference. Bytes are bytes.
Card readers are faster in the transfer, less error prone, do not need any special drivers, and do not drain the camera battery.