Question

What is the difference between base font and font tag

Answer 1

Base font is an HTML tag that specifies the font you want to use throughout your document: 

<basefont face="arial, verdana, courier" size="4" color="green"> 

In this example the browser of the user will select the first available font of the list to display the text. 

The font tag is an older HTML tag but is no longer recommended although it still works. This is an example of its use: 
<p> 
<font size="3" face="verdana" color="blue"> 
This paragraph is in Verdana, size 3, and in blue text color. 
</font> 
</p> 

Answer 2

Base font is empty element.
It is an HTML tag that specifies the font you want to use throughout your document.

Font tag is an container element.
<font>only effects text upto closing i.e., </font>.

i hope the answer will help you.