Copilot Side Pane vs =COPILOT() Function: What You Can and Can't Replace
The =COPILOT() function lived in cells; the Copilot side pane lives in a conversation, and every other difference follows from that. The side pane is better for summarising datasets, exploratory questions, and drafting single pieces of text, and it can see your whole workbook. It cannot populate a column row by row, which means per-row classification, normalisation, and extraction workflows need a third-party add-in, Office Scripts, or Power Query instead.