Lambda function with TEXTJOIN

Hi,

Fist I put this in 365 as itn relates to LAMBDA, if it should be in general , sorry,

I have created a formula to give the columns of two table that are different so

 LET( x,  SEQUENCE(,COLUMNS(Table1[@])) *(Table1[@] <> Table2[@]), TEXTJOIN(", ",TRUE, IF(x=0,"",x) ))

But I wanted to see I could reproduce as a spilled array, I have got as far as this

 MAP( Table146,Table257,MOD(SEQUENCE(4,3,0,1),3)+1, LAMBDA(x,y,z,
                                                      LET( ans,  z * --(x <> y ), IF( ans = 0, "", ans ) )))

which gives the columns / rows with differences,
but I'm not sure about getting TEXTJOIN to work within it? so is there a way? I have attached book with result non lambda
and the above.

Richard.