If you log onto the Solarwinds server and open Solarwinds Network Configuration Manager, you can easily select 2 configs (hold down shift as you select them) and then right click and select Compare Selected Configs.
Or you can do it in the GUI by selecting Configs and then Configuration Management. Then select on the 2 devices you wish to compare. Then click on Compare node configs. This will open a new window. Then you just pick which config in each column that you'd like to compare.
Hope that helps.