This command show you all about all the changes made in the commit, i.e. total number of lines added or deleted:
git diff --stat <commit1> <commit2>
To shows total number of lines added or deleted we use:
git diff --shortstat <commit1> <commit2>
This will show, the total changes,
e.g., "8 files changed, 32 insertions(+), 16 deletions(-)".