Differences between toString of and toLocaleString of in JavaScript

These two methods are used occasionally

Then, when converting numbers into strings, I don't feel any difference between these two methods, as follows:

var e=123
e.toString()
"123"
e.toLocaleString()
"123"

Right, it doesn't make any difference

Let's continue to look at the difference between these two methods when converting arrays into strings. Look, the code is as follows

var aa=[1,2,3]
aa.toLocaleString()
"1,2,3"
aa.toString()
"1,2,3"

It doesn't make any difference

Then look on the Internet and find that there seems to be a difference in the conversion time format, so look at it, the code is as follows:

var sd=new Date()
sd
Wed Feb 15 2017 11:21:31 GMT+0800 (CST)
sd.toLocaleString()
"2017/2/15  Morning 11:21:31"
sd.toString()
"Wed Feb 15 2017 11:21:31 GMT+0800 (CST)"

Well, I can see the difference clearly in this way