why headers of query results display sometimes in button sometimes in links format ?

Question

Hello All,

it's just my curiosity to know that why phpmyadmin behavior in different manner when we modify query a bit( putting extra space) then headers of query results, sometime comes in Button format( on hover it say sort, but sorting not working at all) and sometimes in blue link is there any difference for this or it just causing by some othe reason?

i m attaching both images.

Button headers

Link headers