If you want to compare two folders completely there's a handy diff tool in linux that looks like this: diff -rq folder1 folder2. Unfortunately this does the comparison by content so if you're just trying to figure out which files are in one folder but not the other, then diff is way overkill.
Here's a handy script to compare two folders on linux by filenames only.
#!/bin/bash
# This script compares two directories recursively and lists all files and directories
# that exist in one directory but not the other, ignoring file contents.
# Usage: ./compare_folders.sh folder1 folder2
if [ $# -ne 2 ]; then
echo "Usage: $0 <folder1> <folder2>"
exit 1
fi
comm -3 <(cd "$1" && find . -type f -o -type d | sort) \
<(cd "$2" && find . -type f -o -type d | sort) \
| sed "s|^\t|Only in $2: |; t; s|^|Only in $1: |"