Information, knowledge, learning, implementation, practice, are all related words with different connotations. Understanding in practical terms would require ability of one person to acquire a concept from one person and transfer the same to another person without any packet loss. :)
If all the three people are on the same plane understanding is absolute.If not it is not.There is no midway as is made out in our educations system prevalent today. Either there is understanding or no understanding.Partial or incomplete understanding mostly plays more havoc than no understanding.
Most of the ills of modern man are an outcome of this gap in understanding. What Quran or bible or Bhagvat Geetha says is not understood by the teachers themselves and the result os for the whole world to see.