Doer / Done to

-er

Occupation or pastime

-er combines with verbs to form nouns. Nouns formed in this way refer to people who do the action decribed by the original verb, usually because it is their job. For exemple, a 'baker' is someone who bakes and sells bread and cakes; the 'leader' of a group of people or organization is the person who leads it or who is in charge of it.

He sometimes helped Mr Mueller in the kitchen as a cook and a baker.

The driver went back and started the bus.

I went to London and tried to earn my living as a portrait painter.

She was a student teacher, spending a year in a school in Cambridge.

-ee

Someone who is affected by an action

-ee combines with transitive verbs which describe actions to form nouns. Nouns formed in this way refer to the person that the action is being done to. For exemple, an 'employee' is somenone who is employed by a firm; a 'trainee' is someone who is being trained to do a particular job.

Conflict arose between employer and employee.

...the year's nominee for the exchenge scheme.

...various appointees to lesser points."

Text extracted from Collins Cobuild English Guides 2: Word Formation.

London, HarperCollinsPublishers, 1991. p. 42/48