Учитель (or вчитель, it’s a phonetic variant) has two meanings. When we compare викладач with a day-to-day meaning of учитель, the difference is:
- Викладач usually works in university, учитель usually works at school.
- Викладач just gives knowledge (often to adults), вчитель not just gives knowledge but helps a child to grow as a personality... At least in theory. (I can’t say about Ukraine, but in my country, school teachers are severely underpaid, so the entry barrier is low, and people of questionable moral qualities are often hired.)
- Викладач often does academic research, вчитель usually doesn’t.
Вчитель also has another meaning: it can refer to authority figures, spiritual leaders, people to follow.