Beginner Saving JPEG Baseline Standard or Optimised

[reheat module]

Apologies if this has already been asked, but I'm using Elements and want to know the difference between saving baseline or optimised.
Does it affect quality in any way, and is one better than the other for any special treatment/reason?
Many thanks

 

[jakeblu]

@reheat module From what I remember optimised gives a slightly smaller file but may not be readable by some older browsers, baseline is pretty much standard.