“从来”和“始终”都有“在某一段时间内持续进行”的意思，但在用法上还是有区别的。 “从来”在很多情况下用于表示否定状态，通常为主观上的否定，比如：“他从来都不吃午饭。”而且多数情况下，“从来”的后面会跟上“都”“就”等词来强调。 “始终”也可以用于否定句中，通常指从过去开始一直持续的某种情况，但终处可能在过去、现在或者将来，比如：“他始终不肯说出那件事情的起因。”当用于肯定中时，“始终”表示的是一种经常性发生的动作。例如：“他的声音始终充满魅力。” 另外就是，当一件事情有确定的起点以及终点时，只能用“始终”，不能用“从来”。

给你简单一点的回答吧： give you a simple answer “从来”表示一段持续性的时间，而且还在继续 “always” said a continuous time, and still going on 始终经常表示一个阶段性的过程，从始至终 “all the time" said a phased process, from beginning to end 不过中国人自己都不是特别在意这两个词的区别，他们经常可以替换使用 But the Chinese themselves are not particularly care about the difference between the two words, they often can be used to replace

Both phrases are in similar definition, but indeed there is slightly difference. Both phrases mean always, since, having been, but 從來 emphasizes on the beginning, in the first place, while 始終 puts emphasis on the final result, in the end. Example: John從來不認識Mark。John has never talked to Mark before. John始終沒機會認識Mark。John never has the chance to talk to John, even now. However, 從來 and 始終 are usually interchangeable. Also for the record here, there's a special category of phrases which is unique in Mandarin, we call it 偏義複詞 (compounds of partially semantic shift), compound words like these usually consist a pair of characters with opposite ideas and refer to only one idea out of the two, a semantic shift, so to speak. For example we would say 恩怨(favors & resentment), 好壞(good & bad), and 始終(beginning & end), and 恩怨 actually refers to resentment rather than favor, 好壞 means the bad rather the good, and 始終 emphasizes on the end rather than the beginning. 從來 isn't a semantic shifting compound word, it's just a compound word consisting an identical idea, 從 and 來 both mean the beginning here.