The difference between the Center button and the Merge & Center button is that the Center button does not merge cells.
When you click on the Center button, it will align the text or content in the selected cells to the center both horizontally and vertically, but it will not merge the cells together. This means that each cell will still remain separate and distinct from the others.
On the other hand, when you click on the Merge & Center button, it will not only align the content in the selected cells to the center but it will also merge the cells together into one single cell. This results in one larger cell that spans across multiple columns or rows, with the content centered within the merged cell.
In summary, the Center button simply aligns the content to the center without merging the cells, while the Merge & Center button aligns and merges the selected cells into one larger cell.