A reference letter is a sort of "prepared reference". When you give an employer your references, they're going to ask certain questions regarding your personality (work ethics, communication skills etc.). A reference letter should have these all ready answered in it.
If a job asks for a reference, then give them references, if it asks for reference letters, then you gotta get reference letters. Personally, I wouldn't wanna substitute them for each other.
Reference letters are sometimes used for upper level jobs, and executive positions. Sometimes, they are provided by your previous employer upon your resignation (provided you left in good terms).
To get one from a prof, you should speak with them personally.
And for medical school (cuz i know why you're asking this), the requirements for reference (aka "referee statements) are outlined in the OMSAS application guide.
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Kevin Yin
Chemical Biology IV |Economics (minor)
President, McMaster Undergraduate Society for the Chemical Sciences
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