chmod +X difference

root@kali:~/hackthebox.eu/Access/test# ls -lahR
.:
total 12K
drwxr-xr-x 3 root root 4.0K Nov 22 00:04 .
drwxr-xr-x 5 root root 4.0K Nov 22 00:04 ..
drwxr-xr-x 3 root root 4.0K Nov 22 00:05 dummy

./dummy:
total 12K
drwxr-xr-x 3 root root 4.0K Nov 22 00:05 .
drwxr-xr-x 3 root root 4.0K Nov 22 00:04 ..
drwxr-xr-x 2 root root 4.0K Nov 22 00:06 dummy
-rw-r--r-- 1 root root    0 Nov 22 00:05 f1.txt
-rw-r--r-- 1 root root    0 Nov 22 00:05 f2.txt
-rw-r--r-- 1 root root    0 Nov 22 00:05 f3.txt

./dummy/dummy:
total 8.0K
drwxr-xr-x 2 root root 4.0K Nov 22 00:06 .
drwxr-xr-x 3 root root 4.0K Nov 22 00:05 ..
-rw-r--r-- 1 root root    0 Nov 22 00:06 f1.txt
-rw-r--r-- 1 root root    0 Nov 22 00:06 f2.txt
-rw-r--r-- 1 root root    0 Nov 22 00:06 f3.txt
root@kali:~/hackthebox.eu/Access/test# chmod -R a-rwx,u+rwX dummy/
root@kali:~/hackthebox.eu/Access/test# ls -lahR
.:
total 12K
drwxr-xr-x 3 root root 4.0K Nov 22 00:04 .
drwxr-xr-x 5 root root 4.0K Nov 22 00:04 ..
drwx------ 3 root root 4.0K Nov 22 00:05 dummy

./dummy:
total 12K
drwx------ 3 root root 4.0K Nov 22 00:05 .
drwxr-xr-x 3 root root 4.0K Nov 22 00:04 ..
drwx------ 2 root root 4.0K Nov 22 00:06 dummy
-rw------- 1 root root    0 Nov 22 00:05 f1.txt
-rw------- 1 root root    0 Nov 22 00:05 f2.txt
-rw------- 1 root root    0 Nov 22 00:05 f3.txt

./dummy/dummy:
total 8.0K
drwx------ 2 root root 4.0K Nov 22 00:06 .
drwx------ 3 root root 4.0K Nov 22 00:05 ..
-rw------- 1 root root    0 Nov 22 00:06 f1.txt
-rw------- 1 root root    0 Nov 22 00:06 f2.txt
-rw------- 1 root root    0 Nov 22 00:06 f3.txt
root@kali:~/hackthebox.eu/Access/test# chmod -R a-rwx,u+rwx dummy/
root@kali:~/hackthebox.eu/Access/test# ls -lahR
.:
total 12K
drwxr-xr-x 3 root root 4.0K Nov 22 00:04 .
drwxr-xr-x 5 root root 4.0K Nov 22 00:04 ..
drwx------ 3 root root 4.0K Nov 22 00:05 dummy

./dummy:
total 12K
drwx------ 3 root root 4.0K Nov 22 00:05 .
drwxr-xr-x 3 root root 4.0K Nov 22 00:04 ..
drwx------ 2 root root 4.0K Nov 22 00:06 dummy
-rwx------ 1 root root    0 Nov 22 00:05 f1.txt
-rwx------ 1 root root    0 Nov 22 00:05 f2.txt
-rwx------ 1 root root    0 Nov 22 00:05 f3.txt

./dummy/dummy:
total 8.0K
drwx------ 2 root root 4.0K Nov 22 00:06 .
drwx------ 3 root root 4.0K Nov 22 00:05 ..
-rwx------ 1 root root    0 Nov 22 00:06 f1.txt
-rwx------ 1 root root    0 Nov 22 00:06 f2.txt
-rwx------ 1 root root    0 Nov 22 00:06 f3.txt