var t,n,i,cnt:longint;
    s1,s2:string;
begin
 readln(n);
 for t:=1 to n do begin
  readln(s1);
  readln(s2);
  if length(s1)<>length(s2) then
  begin writeln('No'); continue; end;
  cnt:=0;
  for i:=1 to length(s1) do begin
   if s1[i]<>s2[i] then inc(cnt);
 end;
   if cnt>1 then begin writeln('No'); continue; end ELSE writeln('Yes');
 end;
 close(input);close(output);
end.