It can be quite confusing when you have 2 methods in an API with same names. Hopefully, this post will clear up your doubts.

.each()

Consider the following markup:

<div id="dv">
    <input type="text" value="text box" />
    <p>paragraph element</p>
    <span>span element</span>
</div>

Suppose we want to find out the tag name of each element present inside this div. In this case we will use .each iterator

$('#dv').children().each(function(index, element) {
    console.log('element at index ' + index + 'is ' + (this.tagName).toLowerCase();
});

Output:

element at index 0 is input
element at index 1 is p
element at index 2 is span

each() function takes 2 parameters, index of current element and the DOM element itself. Therefore, this will refer to the DOM element inside each(). We can get the tag name using tagName property of DOM element.(This post explains it in detail). To use the corresponding jQuery object, use $(this)

$.each()

$.each takes 2 parameters. First is the object over which the iteration is to be done and second is the callback function that will execute on each iteration. The callback function provides 2 parameter, first is index of current element(or you can say key in case of objects) in object and second the value at that index.

First, let us iterate over a js array.

var myArray = [10,20,30,40,50];
$.each(myArray, function(index, value) {
    console.log('element at index ' + index + ' is ' + value);
});

Output:

element at index 0 is 10
element at index 1 is 20
element at index 2 is 30
element at index 3 is 40
element at index 4 is 50

Another example using an object:

var myObj = {
"Google" : "http://google.com",
"Reddit" : "http://reddit.com",
"Mashable" : "http://mashable.com"
};
$.each(myObj, function(key, value) {
    console.log('value for key ' + key + ' is ' + value);
});

Output:

value for key Google is http://google.com
value for key Reddit is http://reddit.com
value for key Mashable is http://mashable.com

That’s it. If you still have doubts, let me know in comments.