In order to assess if students truly understand a concept it's necessary to see how the students are processing the information rather than just recording it. Skills involved in processing information may include comparing and contrasting, classifying and analyzing it. Assessing understanding will involve looking at whether students can explain the information, how they use it to make inform their decision making and whether they are able to draw conclusions. This may involve students doing a lot of research, but I still think it's possible to understand a concept without going through the process of inquiry.
Inquiry to me is more applying or using the information in new ways and should involve some evaluation or judgement of the information itself. Students should not only be able to look at how someone else has used the information, they should perhaps be able to speculate and make forecasts based on their understanding of the information. Assessing the inquiry will often involve creation, whereas gathering and processing information may not. Having a good summative assessment, and planning for this at the beginning of the units, is what I think will move our teachers and students away from fact finding and into inquiry.
Photo Credit: The Forbidden Fruit by Brunna Peretti Loureiro