The first statute deals with carnal knowledge of a child between thirteen and fifteen years of age. Therefore, if you are 18 years of age or older and have sex with a 13 or 14 year old minor, that is a Class 4 felony and punishable by 2-10 yrs and up to $100,000 fine.

The second statute deals with someone 18 years of age or older having sex with someone age 15, 16, or 17 years of age, which is a class one misdemeanor and punishable with up to one year in jail and a $2,500.00 fine.

Statutes covering sexual relations between minors can be understood by the second paragraph in statute § 18.2-63

"However, if such child is thirteen years of age or older but under fifteen years of age and consents to sexual intercourse and the accused is a minor and such consenting child is three years or more the accused's junior, the accused shall be guilty of a Class 6 felony. If such consenting child is less than three years the accused's junior, the accused shall be guilty of a Class 4 misdemeanor."

§ 18.2-63. Carnal knowledge of child between thirteen and fifteen years of age.
If any person carnally knows, without the use of force, a child thirteen years of age or older but under fifteen years of age, such person shall be guilty of a Class 4 felony.

However, if such child is thirteen years of age or older but under fifteen years of age and consents to sexual intercourse and the accused is a minor and such consenting child is three years or more the accused's junior, the accused shall be guilty of a Class 6 felony. If such consenting child is less than three years the accused's junior, the accused shall be guilty of a Class 4 misdemeanor.

In calculating whether such child is three years or more a junior of the accused minor, the actual dates of birth of the child and the accused, respectively, shall be used.
For the purposes of this section,

(i) a child under the age of thirteen years shall not be considered a consenting child and

(ii) "carnal knowledge" includes the acts of sexual intercourse, cunnilingus, fellatio, anallingus, anal intercourse, and animate and inanimate object sexual penetration.

§ 18.2-371. Causing or encouraging acts rendering children delinquent, abused, etc.; penalty. Any person eighteen years of age or older, including the parent of any child, who

(i) willfully contributes to, encourages, or causes any act, omission, or condition which renders a child delinquent, in need of services, in need of supervision, or abused or neglected as defined in §16.1-228,or

(ii) engages in consensual sexual intercourse with a child fifteen or older not his spouse, child, or grandchild, shall be guilty of a Class 1 misdemeanor. This section shall not be construed as repealing, modifying, or in any way affecting §§ 18.2-18, 18.2-19, 18.2-61, 18.2-63, 18.2-66, and 18.2-347.
(Code 1950, § 18.1-14; 1960, c. 358; 1975, cc. 14, 15; 1981, cc. 397, 568; 1990, c. 797; 1991, c. 295; 1993, c. 411.)