"able" is an adjective...." ability" is the noun..and " to enable" is the verb If someone is " able " to do something = they can do it and it is not unusual or surprising if they do it. e.g :" Will you be able to play on Friday?" "enable"= make someone able to do something e.g:" This scheme is designed to enable young people to find work "

able = adjective enable = verb Their different meanings are in the dictionary.