Stereo, hi fidility, ultra hifidelity ?

Can one of you smart Analog people me what to look for on an LP with regard to how the LP was recorded. I got a few questions.....
Went to purchase an LP the other day and found out that there are LP's recorded in stereo. Thats easy enough. But what does 'Hi Fi' on a jacket cover mean. Is that the same as stereo? What about 'Hi Fidelity' and 'Ultra Hi Filelity'? Oh, and what does 'MS' on a jacket cover mean ?

I was told that at some point, 'Stereo' recordings became the norm hence the word was not even put on the LP covers.

If there is a difference in recording methods, does it make much of a difference ? Thanks in advance....,.