Well, LM386 and JRC/NJM386 have same pinout, so they are to some extent interchangeable. Their internal circuitries are not the same.
There are different versions of LM386:
LM386N-1
LM386N-3
LM386N-4
You can use LM386N-1 with 4-12V power supply (absolute maximum ratings 15V)
For LM386N-4 you can use 5-18V supply (absolute maximum ratings 22V)
JRC/NJM386 have operating voltage of 4-12V (absolute maximum ratings 15V)
Both have same voltage gains from 20 to 200, same THD 0.2%.
Also there is a LM /JRC 386B.
LM386B have operating voltage of 5-18V (absolute maximum ratings 22V), THD 0.1%
Datasheets:
http://www.ti.com/lit/ds/symlink/lm386.pdfhttp://semicon.njr.co.jp/eng/PDF/NJM386_E.pdfhttp://users.ece.utexas.edu/~valvano/Da ... LM386b.pdfFor a tonal differences and preferences you are the judge.