欢迎 (huān yíng) is the everyday verb for 'to welcome' — used to greet someone to a place or event, and common in polite formulas like 'welcome to...'. 迎接 (yíng jiē) is more specific: it means to go and meet someone when they arrive, and is slightly more formal. 迎 (yíng) is a literary single-character verb used mainly in fixed expressions or formal writing.