It never ends there, does it? Our choice of beginnings, endings, and turnings reinterpret all else that was said. Introductions hold the power of context: one shapes the way what follows will be seen. Conclusions hold the power of interpretation: one has the potential to re-create the entire previous discussion. Turnings and other conjunctions define personal relationship to what has immediately preceded.
"But" negates everything that went before. "I agree with you, but ..." Another word of the same type is "however". "Although" and "despite" are even stronger: not only negating what was said before, but emphasising its lesser importance to the qualifying condition. A teasing example: "He dresses well, even though he is a man."
In contrast, "and" reinforces an association between thoughts: "I just saw an accident and it is going to rain." Regardless of whether the two ideas have any independent linkage, the speaker has linked them in their mind -- and the choice of word encourages the listener to do likewise.
Curious, the power of a word.