Implicit Learning vs. Latent Learning
Implicit Learning


  Implicit learning refers to situations in which complex information is
  acquired effortlessly (without a conscious effort), and the resulting
  knowledge is difficult to express verbally. (Italics mine)


As discussed in the Wikipedia page, the exact definition is controversial, but all the paradigms (verbal reports, forced-choice tests, etc.) listed, the knowledge is gained unintentionally and without awareness. 

Both these criteria relate to the learner's subjective relationship with the acquired knowledge. It says nothing about behavior and reinforcement, which may be readily apparent.

Consider social skills as an example. I may smile, gesture, and make eye-contact appropriately (behavior), and I experience positive social outcomes when I do so (reinforcement). However, I never explicitly set out to learn the number of milliseconds to maintain eye-contact, or what situations warrant a smile. Moreover, if someone offered to pay me to write instructions on how to engage socially, I would have a hard time articulating my knowledge. It is implicit.

Latent Learning


  Latent learning is defined as learning that occurs in the absence of
  any obvious reinforcement or noticeable behavioral changes. (Italics mine)


These criteria relate to the objective behavior and circumstances of the learner. It says nothing about the learner's subjective awareness of the knowledge.

Consider the bus ride example. I may be perfectly aware that I am gaining knowledge of the bus route through observation. But an objective observer would have no way of proving that I have learned the route: I behave the same as if I had not learned it, and I receive no clear reinforcement for doing so. However, if someone offered to pay me to give directions to my work place, I would be able to do so. My knowledge is explicit but hidden.

To sum it up very roughly:

Implicit learning is when the knowledge you gained isn't apparent to you.
Latent learning is when the knowledge you gained isn't apparent to others.