also: エスカレータ
noun
escalator
Standard loanword for a moving staircase, used in everyday Japanese.
駅のエスカレーターはいつも混んでいる。
The station escalator is always crowded.
Shorter variant without the final long vowel; less common but still seen.
階段 means a regular staircase or stairs, while エスカレーター specifically refers to a mechanical escalator.
Borrowed from English 'escalator'. The shorter form エスカレータ reflects a common tendency to drop final long vowels in some loanwords.