dem - Comparing two TINs created using ArcGIS for Desktop?

I have the following two files:

1. LiDAR las file1



2. Let's give it a name LiDAR las file2, contains the same file1 data, where number of points randomly removed.

So if file1 contains X number of points, file2 would contain Y number of points, where Y is less than X.

Now, I am using ArcGIS "LAS to Multipoint" to create from both files above their shape counterparts. Next I am creating two empty TIN(triangulated irregular network) files using ArcGIS. Then I edit both TINs, let's say tin1 and tin2, with the appropriate input feature classes, i.e. file1 to tin1 and file2 to tin2.

Is there any tool/package/library or any software that would let me calculate the RMSE(root mean square error) or any difference information that would give me information on the accuracy of the second file, i.e. file2, with respect to file1? I tried to use the TIN difference but it gives system error and cannot obtain the result. I would really appreciate if anyone could show how to obtain accuracy information and interpretation of the results obtained.