Difference between 'As compared to' and 'When compared to'

Is there any rule governing when the phrase "As compared to..." should be used, and when "When compared to..." should be used? Or, do they mean the same, in all contexts?

Solution 1:

Please see this :

Both forms occur in objective writing, but "when compared to" occurs more often in personal and persuasive writing.

"As compared to" is the standard form in the reporting of statistics from research. It's used in scientific, technical, and business writing. It's very impersonal.

"When compared to" is a short form of "when one compares (X) to (Y)," and is used when the act of comparison itself is relevant. This form also occurs in persuasive writing, when the writer seems to be asking the reader to do the comparing. Given the context, Sentence 1 is more appropriate.