It's a pretty important legal difference. The administration is now trying to treat it as a criminal offense, trying to enforce it as a criminal offense, using that to justify calling huge swathes of immigrants 'criminals', etc.

Consider this scenario. A friend of yours walks up to you and says "man, I got a ticket yesterday." You will have a general idea of the level of enforcement involved, how that's looked at by the government and others, etc. You probably do not see your friend as a criminal.

Now, suppose the same friend walked up and says "man, I got arrested yesterday, I just got bailed out." You will have different ideas of the enforcement model and perceptions of that. There is now a greater probability that you see your friend as a criminal.