Additionally... you can say "Lavora come un mulo" (he/she works like a mule) to say that somebody works hard.
If secretaries would be well known to have a certain style of working, you could say that somebody is working "like a secretary" (come una segretaria).
I doubt this could ever be the case, but you never know...
Why this doesn't need the article, as in "la mia sorella"? Is there some kind of a rule for when you can leave it out? :)
When indicating an occupation, "lavorare come" is used without an article, "essere" is used with an indeterminate article and "fare" is used with a determinate article.
Family members in the singular do not take the definite article with the possessive.
How come my mother is a secretary is "mia madre fa la segretaria" but this is "come segretaria" if you know what i mean?
Different constructions? One is "fare <definite article> <occupation>" and the other is "lavorare come <occupation>".
It can be used to mean "like" or "as". Doesn't mean the translations are equivalent.