一路 (yī lù) means 'the whole journey; all the way' — it can be a noun (the entire trip) or an adverb (throughout the journey, or going the same direction). 一直 (yī zhí) is a broader adverb for 'continuously' in a temporal sense, not specific to a trip; 全程 (quán chéng) is a more formal noun for an entire course or process, often used in official contexts.