Another thing that I note is that if you have an alias like this:
# add into .bashrc_aliases
alias ls='ls -lht'
With ./test.sh you'll get a normal ls output (and a different PID than current shell):
auraham@pandora:~/iso$ ./test.sh
dsl-4.4.10.iso test.sh
3136 # PID
With . test.sh or . ./test.sh you'll get a more detailed output (and the same PID than current shell):
auraham@pandora:~/iso$ echo $$
2767 # shell PID
auraham@pandora:~/iso$ . test.sh
total 50M
drwxrwxr-x 2 auraham auraham 4.0K Jul 30 15:41 .
-rwxrwxr-x 1 auraham auraham 32 Jul 30 15:41 test.sh
drwxr-xr-x 50 auraham auraham 4.0K Jul 30 15:30 ..
-rw-rw-r-- 1 auraham auraham 50M Jul 28 17:24 dsl-4.4.10.iso
2767 # PID