ターポリン is a direct loanword for 'tarpaulin', often used in industrial or marine contexts, while 防水帆布 is a native compound emphasizing the waterproof canvas material.
シート is a general term for a sheet or cover, not necessarily waterproof or heavy-duty, whereas 防水帆布 specifically denotes waterproofed canvas.
Compound of 防水 (waterproof) and 帆布 (canvas, sailcloth). The term transparently describes the material's function and composition.