In Numbers, you have multiple tables that are entirely separate row:column spaces that can be resized and positioned arbitrarily and independently, with small finite extent by default such that they fit on screen. That UI makes the capability to have multiple tables on one sheet more discoverable, and easier to comprehend what it's doing. When you drag and drop a CSV file onto a Numbers sheet, it creates a new table rather than populating cells in an existing table. When you resize column A in one table, it doesn't affect the column A of any other table.

That finite vs seemingly-infinite distinction is a fundamental difference in conceptualizing what a spreadsheet is, which can have pretty far-reaching consequences. I've encountered programs with a "CSV export" feature that generates a CSV file that's more or less what you'd expect to get if you wrote a report in a single Excel sheet, and then exported that to CSV: you get a file that contains tabular data embedded in it, but so polluted with unrelated text and unstructured metadata that having it as CSV format barely helps with parsing and you'd be better off trying to extract data from HTML.