One can say: He likes swimming or He likes to swim. What is the exact meaning of each of these? What is the difference?
The two are often interchangeable but not always. While he likes to swim always means that he enjoys propelling himself through the water using his own body power, he likes swimming could also be used if he enjoys watching it as a spectator:
"The Olympics are on- we could watch swimming or running. Isn't Bill coming over? He likes swimming, so we should watch that."
The two are interchangeable. "He likes swimming" means "He likes the act of going to swim." They mean the same thing and you can say either.
There is an interesting commentary on the similarities and differences between like + gerund and like + infinitive here. I have not yet finished digesting it but there is definitely some food for thought there, for both EFL teachers and students on this issue.