Now, spot the difference! ;-)

$ diff -u \
   <( perl -Mstrict -Mwarnings -MO=Concise -e'my ($u, $v)    = split /
+,/, "U,V";' 2>&1 ) \
   <( perl -Mstrict -Mwarnings -MO=Concise -e'(my $u, my $v) = split /
+,/, "U,V";' 2>&1 ) \
&& echo same
same
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PS, I usually use -MO=Concise,-exec

1  <0> enter
2  <;> nextstate(main 1 -e:1) v:*,&,{,x*,x&,x$,$
3  <0> pushmark s
4  <$> const[PV "U,V"] s
5  <$> const[IV 3] s
6  </> split(/","/)[t3] lK/IMPLIM
7  <0> padrange[$u:1,2; $v:1,2] RM/LVINTRO,range=2
8  <2> aassign[t4] vKS
9  <@> leave[1 ref] vKP/REFC
-e syntax OK
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