ex- vs later

ex-

• former, but still living (almost always used with a hyphen) 

• out of 

• outside 

• Lacking. 

later

• At some time in the future. 

• Coming afterward in distance (following an antecedent distance as embedded within an adverbial phrase) 

• Coming afterward in time (used with than when comparing with another time). 

• Afterward in time (used with than when comparing with another time). 

• At some unspecified time in the future. 

• See you later; goodbye.