So how do you get the information from Excel (or other source) into the web version. You just copy and paste. And it works with huge amounts of data. It's processed all in the browser.*
So, first of all, and most basically, the items in the list do not need to be in any specific order. This automatically makes it very different from most comparison tools.
But there are other smarts. For example, let's say numbers are formatted differently. No problem. Let's say someone enters 150 instead of 510. No problem (slide 4). Let's say someone enters Jan 10 2014 and that is compared to 1/10/2013. No problem (slide 5). Let's say one set of numbers on the left, for example, are positive (+) and the corresponding numbers on the right are negative (-). No problem (slide 8).
Even further. Let's say one email list has Larry Dale <firstname.lastname@example.org> and another has email@example.com. No problem (slide 9). It's still considered a match.
Now let's say you you need to export it back to Excel. No problem (slide 10). And there's a way to get the correct cell number in the results so it's easy to track back the results to the original source.
More to come.