Hair properly split, it's a distinction without a difference.
It absolutely is not. The distinction between something being a crime and it merely being illegal is of great significance, whether the majority of people realize it or not. That significance is particularly evident when it comes to the general subject underlying the issue in this thread - immigration law and enforcement. The reality that deportation is not a punishment legally, and illegal presence is not a crime, makes a huge systemic difference when it comes to immigration enforcement. I suspect most of the people that post in these forums would not like what it would mean if deportation was treated as a criminal, rather than a civil, matter.
Virtually all reasonable people consider performing an illegal act a crime. The minutia of the term notwithstanding.
That may be true when they speak in the abstract, but I don't think it's true when they speak in consequential terms. Do you believe that most people that have at some point in the past had a speeding ticket, consider themselves to be criminals? Do people that filed an illegal application somewhere (i.e. one that didn't meet the requirements of relevant law) consider themselves criminals? Would you consider someone that built a shed that didn't originally conform to some code requirement, and who had to redo it so that it did, to have committed a crime?
At any rate, the issue here isn't what most people consider with regard to the synonymousness of illegal and criminal. Perhaps it might be a bit of hair splitting if someone were to insist that people, speaking colloquially, were in error when they considered something being illegal to be the same as it being criminal. But that is not the situation here. People have made statements that imply (quite accurately) that some illegals haven't committed crimes. Others (here and in other threads) have suggested that that indicates that they don't know what the term illegal means. That latter suggestion is inaccurate - an inaccuracy that is certainly worth pointing out when it itself is a mistaken assertion that someone else was mistaken. I merely pointed that out and then, in response to inquiries, explained to some degree why that is the case.
The simple reality is that illegal presence in this country is not a crime (except for under particular circumstances). If someone indicates that it is not, they are not mistaken. If someone says that they are, then it is they that are mistaken. Pointing out that the former someone is correct is not hair splitting - it is correcting a mistake by the latter someone.