Both are violence criminal offences. The main difference is the consent of the victim (children for example are not capable of giving informed consent to any sex act).
If the victim is from 16 to 18, case per case if being evaluated to decide if abuse has indeed taken place.
For children minor than 16, the law recognised that children are not capable of giving any consent.
If the victim is minor that 16 years, then it can imply up to 3 years of imprisonment, even if no physical meeting has taken place.
For victims younger than 16 years, the arguments are focused on unravelling the credibility of the concerned.
If victim is older than 16 and the offender has already been identified, the focus will be on the consent of the victim.
Yes. Since 1st March 2016, a Sex Offender Registry (Registro Central de Delincuentes Sexuales) exists, reporting all the data related to the identity of finally convicted offenders, including their DNA.
Only magistrates, judges, public prosecutors and judiciary police can get access to the Sex Offender Registry. However, any person working with children can ask for a certificate to prove that he/she does not have any record.