Need local bus info

A real Newbie question to which I can't find the answer on a search: We see buses with both yellow and red writing going down Constitucion in Ajijic. How to tell which are going to Chapala or Walmart? Fare? Pay when you get on or off? Thanks!

If the bus is headed in the direction of Walmart or Chapala, from wherever you are located, it is a safe bet that it will get you there. The fare will vary from 5-9 pesos, or less if you show an INAPAM card.
The only exception will be a bus labeled Guadalajara Directo, which will get you to a stop near the intersection at Walmart, but not to Chapala.