There is no real difference between your two phrases, both include the preposition a and the article el, and for the same resasons.
About the a preposition, in Spanish (in English, too) there are verbs that are usually used with a given preposition.
Which preposition? you just have to memorize them. But note that when translating between English and Spanish those prepositions usually don't match.
For example, in English, "listen" is used with "to":
I'm listening to music.
But in Spanish, "escuchar" uses no preposition:
Estoy escuchando música.
Another example, "dream" is used with "of" or "about":
Dream of me.
While in Spanish, "soñar" is used with "con" (or sometimes "en"):
Sueña conmigo.
Likewise, in Spanish, "jugar" is used with "a":
I'm playing football.
Estoy jugando al fútbol.
About the el article, it is just that in Spanish, sports, and other similar activities, are normally used with a definite article:
Me gusta el ajedrez.
Vamos a ver el fútbol.
No sé jugar al tenis.
Except when the sport itself works as an adjective, then there is no article:
Una partida de damas.
Un jugador de baloncesto.
Un balón de fútbol.