Every two weeks, the difficulty adjustment algorithm compares the number of blocks over the previous two weeks with the expected number of blocks, given a target block interval of ten minutes, and adjusts the difficulty up if there's too many blocks or down if there are too few blocks.
This is not true.
The algorithm compares the average block time of the 2016 blocks mined in the last difficulty period with the expected average block time which is 10 minutes.
Note that the difficulty period may be more or less than 2 weeks.