Trying again because my first comment doesn't seem to have posted: steps are items, stairs are a group. So, "three flights of stairs" but "one step up from the sidewalk." Though I would say/write something like "she sat on the bottom stair."
Instinctually, I would say that flights of stairs are made out of steps. You can have just one or two steps, in isolation, but stairs always have at least three steps per flight, and usually more like four to ten steps per flight.
Assuming you are considering these words only in the context of physical items you can use to change elevation, I believe stairs are made of individual steps. In practical usage, for stairways that are outdoors or less than half a story, I would call them steps, otherwise stairs. "I climbed up the front steps, then I went inside and took the stairs down to the basement."
Stairs are groups of steps but only if they're arranged in the usual way, all in a row (or spiral or maybe some other regular formation), sloping up or down, so that you can ascend or descend them in sequence. Sometimes I may call an individual step a stair, but only if it's part of a group of stairs; I'd feel weird referring to a lone step that way. Or to a step that's part of a haphazardly arranged group, that isn't arranged as stairs.
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Date: 2018-12-19 03:14 am (UTC)(no subject)
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Date: 2018-12-19 07:43 am (UTC)(no subject)
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Date: 2018-12-19 09:11 am (UTC)How'd I do?
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Date: 2018-12-19 01:00 pm (UTC)I think if I look at my head, I mostly use steps for a set of them that aren't enclosed and are outdoors?
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Date: 2018-12-19 01:31 pm (UTC)(no subject)
From:steps and stairs
Date: 2018-12-19 07:09 pm (UTC)Re: steps and stairs
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Date: 2018-12-19 10:33 pm (UTC)(no subject)
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Date: 2018-12-23 04:40 pm (UTC)