Very different (5,5)
I believe the answer is:
poles apart
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">very different</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for poles apart that I've seen before include "Differing greatly" , "widely separated" , "Completely different" , "having nothing in common" , "with widely differing views" .)