Different sites report different blockchain sizes. Some of that might be explained by base-2 or base-10 sizes, but that's not enough to explain the large difference between the extremes.
Is there a site that accurately reports in bytes both the raw size and Core's on-disk size (without the UTXO set)?
201.57 GB (= 187.72 GB
2 if it's GB
10) -
BitInfoCharts (block 527,582)
178.99 GB (= 192.18 GB
10 if it's GB
2) -
Coin Dance171,292 MB (= 179.61 GB
10 if it's MB
2) -
Blockchain.info (updated once per day)
161.20 GiB (= 173.08 GB
10) -
Bitcoin.comThere are disparities like this since they are using fast synchronizations. Other web application in your list with larger blockchain file sizes are using the full on option. This is just about the parameters that they use when syncing with the Bitcoin blockchain. The disparity that you examining are not intended to modify the whole blockchain itself. It is not even intended to create doubt. They are just avoiding the lag that they will experience if they download the whole blockchain in their blockchain file folder.