If the page is immediately read from the row-buffer (or a row-buffer hit), it has the shortest memory access latency in one memory cycle. If it is a row buffer miss, which is also called a row-buffer conflict, it is slower because the new page has to be loaded into the row-buffer before it is read.
When the page is directly fetched from the row-buffer (or a hit), it has minimal memory access latency in one cycle. However, if there's a miss in the row-buffer, which is referred to as a conflict, accessing the new page requires loading it into the row-buffer first before reading.