What is difference in Character size and Character Max Size

I'm trying to limit the amount of characters that a client can enter into a field on one my forms. Listed in the options is "size" and another that says "max size". both have identical descriptions. Please explain the difference. Thanks. 

Thank you for contacting us. 

Option "Size" is width (size) of the field and option "Max Size" is maximum allowed number of characters that can be entered inside of the field. 

I have made demo form with two text box field. Size of first field is 10 and size of second field is 30. You can see that second field is wider.

And both fields have Max size set to 5 characters. 

Here is my demo form: https://form.jotform.com/60195609535965

Hope this will help. Let us know if you need further assistance.