be another/a different matter
be another matter
To be a separate and very different situation, topic, idea, etc., that has a whole other set of difficulties or problems to consider or contend with. It's all well and good wanting to help your fellow man, but inviting strangers off the street to come live with us is another matter entirely!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
be another/a different ˈmatterbe very different: I know which area they live in, but whether I can find their house is a different matter altogether.
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