Sexual interactions with a minor are illegal in every sense of the word, but there are a lot of different variations of these illegalities. The fact of the matter is that there are actually a lot of different ways in which a minor could be harmed through sexual contact, and each of these ways deserve their own classification because of the fact that they cause different kinds of damage to the psyche of a child.
Molestation is one charge that can be levied against someone that has had sexual relations with a minor, but the general legal term that is most often used is “carnal knowledge”. Essentially, if you have carnal knowledge of a minor you had crossed a line and possess intimate details that you should not. Traditionally carnal knowledge has been used to describe relationships outside of marriage, adultery as it were, but now that adultery is not illegal anymore, and has been that way for quite some time, this language is no longer used to refer to this particular kind of sexual activity. However, it is still used when it comes to minors, mostly because the legal language has not changed and the term is interchangeable with terms such as statutory rape.
However, it should be noted that carnal knowledge tends to be a lesser charge than statutory rape. It is usually reserved for adults that are not that much older than the minor that they have had sex with, such as an eighteen year old that has had sex with a fifteen year old. The thing about situations like this is that there is not as much malicious intent, it is not quite the same as a thirty year old having sex with a fifteen year old and there is usually not the sort of power dynamic and imbalance of power that the latter of the aforementioned forms of sex crimes involves. In carnal knowledge, a crime has been committed but it is not as severe as other forms of the same crime.
What this means is that it is very possible that you get off without having to go to jail because of the fact that such things could potentially be taken as a misdemeanor. However, this does not at all mean that carnal knowledge will never result in jail time. If you are convicted it is very possible that you could go to jail if your actions are treated like a felony rather than a misdemeanor.
At the end of the day, the only thing that truly matters is how good your lawyer is. If you have a good lawyer, you are going to end up getting all the help you need, and you could potentially not go to jail at all as long as you are willing to register as a sex offender. That being said, sometimes even the best defenses fail and there is nothing you can do about it when it happens.