What is the difference between 我给你讲 and 我跟你讲? These two phrases both seem to translate to I told you. But when would one be preferable to another?
給 = Give/Let, 跟 = With/Together. When used with another verb together, "給" designate the "transceiver" / "receiver" of the verb, while with "跟", both party are the subjects.
The examples you chose is a indistinguishable case (there are probably a lot of them). Let me elaborate with something else:
- 我給你吃飯 = I let you eat
- 我跟你吃飯 = I eat with you
- 你給我吃飯 = You let me eat
- 你跟我吃飯 = You eat with me / You and I eat together
- 我給你休息十分鐘 = I give you 10 minutes to rest
- 我跟你休息十分鐘 = I rest for 10 minutes with you
- 你跟我休息十分鐘 = You rest 10 minutes with me / You and I rest for 10 minutes together
- 我給你看看 = I'll show you this / (I give you a look of this)
- 我跟你看看 = Let's see this / (I look at this with you)
As for your examples, I guess we can distinguish them literally with:
- 我給你講 = I give you a speech
- 我跟你講 = I speak with you
However, the physical actions of these two are probably not distinguishable from each other.