this and $(this) refers to the same element. The only difference is the way they are used

‘this’ is wrapped in $() then it becomes a jQuery object

let example to understand:

$(document).ready(function(){
$('#spnValue').mouseover(function(){
alert($(this).text());
});
});
$(document).ready(function(){
$('#spnValue').mouseover(function(){
alert(this.innerText);
});
});

‘this’ is used in dom sense, when ‘this’ is wrapped in $() then it becomes a jQuery object and you are able to use the jQuery library.

In the second example, I have to use innerText() to show the text of the span element as this keyword is not a jQuery object yet. So I have to use the native JavaScript to get the value of span element. But once it is wrapped in $() then jQuery method text() is used to get the text of Span.