When using Google Ads, there are two main ways to measure conversion: converted clicks and conversions. Conversions are the total number of conversion actions or total sales plus
unique leads. Converted clicks are the number of clicks that lead to one or more conversions. This metric is useful when you are interested in seeing clicks that generate one or more leads (regardless of the conversion action).
For Example, Bob clicks on your ad once. Then he proceeds to sign up for weekly newsletters and buys a product from your website. Bob has completed two different conversions stemming from your advertisement. When assessing the purchase, Bob has only made one "converted click" even though there were multiple conversions after.
Both converted clicks and conversions are useful metrics when applying conversion tracking and analyzing what happens after a customer actually clicks on your ads.
Limitations to Converted Clicks
can't exclude the conversion actions from converted clicks when using the "include in conversions" settings in Adwords
since one click can generate multiple conversions, converted clicks can't be segmented by name, source, or category
converted clicks cannot be assigned a specific value, whereas conversions can. Therefore you can't compare relative values from converted clicks because they could both lead to very different conversions
converted clicks don't show offline conversions (omit in-store visits, follow-up phone calls, or cross-device follow-up purchases)
In September 2016, Adwords partially removed converted clicks from their program. More specifically, they have removed the conversion bid metric and intend on removing the reporting metric in the near future. For more information, read this article.