How to install 2.80 without disturbing 2.79 installation?

[gk]

How to install 2.80 without disturbing 2.79 installation?
The INSTALL file with make 3.80 doesn't really cover this. I am not clear 
on the effect of various ./configure options

I would like to install 3.80 but do not want to overwrite make 3.79 
executable or info files.
I need to test my makefiles with both versions.
$make # should run 3.79
$make380 # should run 3.80
$info make # should run info with make 3.79 file
$info make380 # should run info with make 3.80 file

Thanks.

- Greg Keraunen