役 and 役割: a doctor in a play, moderators and a forest
Compare 役 as a theatrical part or moderator's task with 役割 for moderation and a forest's function. Preserve the overlap while identifying who or what has the role.
役 in a theatrical part and moderation
役 (やく) means role or part. 「劇で私は村の医者の役を演じた。」 means “I played the village doctor in the play.” The village doctor is the character played in the drama. This theatrical part does not identify the speaker's real occupation.
「司会は話し合いを円滑に進める役を担う。」 means “The moderator's role is to keep the discussion moving smoothly.” The moderator's task is to keep the discussion moving smoothly. 役 therefore appears with a moderating function as well as a theatrical part.
役割 in a moderator's task and a forest's function
役割 (やくわり) means role. 「司会者は話し合いを進める役割を担う。」 means “The moderator's role is to guide the discussion.” Guiding the discussion overlaps with the moderator example using 役.
「森は多くの生き物を支える役割も果たしている。」 means “Forests also play a role in supporting many living things.” The forest has the function of supporting many living things. This use concerns a forest's function, rather than appointment to a human job.
Overlapping tasks and different role holders
The moderator examples use both 役 and 役割. Restricting the first word to acting or the second to human jobs would lose that overlap and the forest example.
村の医者の役 identifies a portrayed character, while 話し合いを進める役割 identifies a task. The forest's support function shows how the holder and object of a role can differ.
Does 劇で私は村の医者の役を演じた establish that the speaker really is a village doctor?
Show the answer and why
It states that the speaker played the village doctor in a drama. It does not establish that real occupation. Read the moderator's task and the forest's support function through their respective role holders.