Are “walk through” and “talk through” the same?
Not exactly. “Let me walk you through this” is like “Let me explain this in a way that you can understand,” whereas “Let me talk you through this” is more like “Follow my instructions and do exactly what I tell you.”
According to Oxford, to “walk someone through” means to “guide (someone) carefully through a process” while to “talk someone through” means to “enable someone to perform (a task) by giving them continuous instruction.”
To my feeling, ‘walk through’ has to do with explaining an entire process, which may require further instruction or reinforcement at a later date, or explaining specifically how something occurred in the past and in what order it occurred; whereas ‘talk through’ has to do with giving immediate, specific instructions to complete a task at hand, although I have no doubt that these two expressions are often used interchangeably by native speakers.
Examples of what I consider proper use, taken from the internet:
Teaching an elderly person how to use a computer:
“The keyboard can be adjusted for someone in a wheelchair,” he said. “And with the touch screen, she doesn’t need to use a mouse, which is more difficult. We walked her through it and she got pretty good at remembering the steps.”
Getting a person safely through a dangerous passage in a cave:
“The second cave we went into was particularly adventurous. It had a stream running through it, and we swam through body-sized crevices and tunnels with just our eyes and mouths peeking out of water. This is definitely not for the claustrophobic. Upon seeing the first narrow passage one woman in our group nearly got a panic attack, but we talked her through it, and she courageously made it all the way to the end of the cave, which is where the water suddenly drops into a magnificent waterfall.”