Ir+A+Infinitive vs. Future Tense

It's just like in English:

Ir + a + infinitive = going to do something
Voy a caminar mañana = I am going to walk tomorrow

Future tense = will do something
Caminaré mañana = I will walk tomorrow

In college, I had a professor (not a native speaker but someone who had lived in Latin America for much of her life) said she typically used ir a + infinitive. I guess it's the same way as it is with English. I say "going to" far more often than "will."

"Ir+a" is more natural in spoken language. Future tense is still common in written texts.

In some contexts, future expressses uncertainty: "¿Lo haremos?" (Will we do it, by chance? / I wonder if we will do it), "Será su madre" (It's her mother, perhaps).

"Voy a seguir" esta conversación...... seré más informed.?

I got away with not knowing simple future at all for the first fifty years of my life and only using the ir + a form in Spanish. However, it's good to be a be able to recognize the simple future. I have noticed that simple future is used a little more in TV programs from Spain "Yo lo haré" as compared to Mexican programs "Voy a hacerlo."

this is a crazily complex question as the difference can not only demonstrate subtle changes to possibility, certainty, and probability, but also implicitly show when a decision was made rather then when it will occur. Throw in regional differences, and set structures such as conditionals and it all becomes a mess for a long time. I would strongly suggest not focusing too much on the technical difference and start getting a feel for when one should be used rather than the other

It's a matter of formality, for the most part. I would almost never write using the phrasal (ir + a + infinitivo) future on anything even remotely formal, like a school essay, but I would certainly use it in conversation. Region also matters, as has already been said. The simple future tense is more common in Spain, phrasal future tends to be more common in Latin America, so it'll depend somewhat on what Spanish you learn and where you speak it. But for me (and my Spanish learning has leant more toward Spain in its regionalisms, to give you an idea of my own personal quirks and biases), I decide between the two based mostly on formal context and a little based on verbal aspect.