Okaasan is correct.
For this particular phrasal verb, it is possible to distinguish between 'off' and 'out' just as she did.
In fact, the particles 'off' and 'out' are added to many verbs, making another special meaning for each two-word phrase.
So, it's necessary to know the meaning of each verb + particle (little word) combination separately.
As for the definitions of 'off' and 'out' -- well, take a look at these two entries from the LDOCE:http://www.ldoceonline.com/search/?q=offhttp://www.ldoceonline.com/search/?q=out