Dual pane diff, hide common lines

Two files

one.txt     two.txt

a           d
b           e
c           f
d           g
e           h
f           i

meld way (the correct looking way, don’t know how to hide common lines yet, but this is a search for a cli tool.)

meld

diff way (the other way)

diff -y --suppress-common-lines one.txt two.txt

a  < # I'd expect this to be >
b  <
c  <
>  g
>  h
>  i

# The other way?

diff -y --suppress-common-lines two.txt one.txt
    
   >  a # really?
   >  b
   >  c
g  <
h  <
i  <

comm –help

-1              suppress column 1 (lines unique to FILE1)
-2              suppress column 2 (lines unique to FILE2)
-3              suppress column 3 (lines that appear in both files)

comm way (neat, small, readable?)

comm -3 one.txt two.txt

a
b
c
        g
        h
        i

Other tools, https://news.ycombinator.com/item?id=32746258