on the way; en route
Refers to being in the course of moving from one place to another, or during a journey. Often used with verbs of movement or stopping.
I met a friend on the way to school.
帰宅の途中、スーパーに寄った。
On the way home, I stopped by the supermarket.
in the middle of; midway; halfway
Indicates being partway through an action, process, or state, not yet finished. Common with nouns like 仕事, 会議, 食事, or verbs in ている form.
食事の途中で電話が鳴った。
The phone rang in the middle of the meal.
まだ工事の途中です。
It's still in the middle of construction.
I stopped at a convenience store on the way to the station.
The phone rang in the middle of the meeting.
I stopped doing my homework halfway through.
I changed my mind partway through the trip and decided to go home.
道中 is a somewhat old-fashioned or formal word for the course of a journey, while 途中 is the plain, everyday word for 'on the way'.
途中 is the common, casual word for 'on the way' or 'midway', while 途上 is more formal and typically appears in set phrases like 発展途上国.
途中 emphasizes being partway through a process or journey, while 中ほど focuses on the physical or sequential middle point itself.
dropping out mid-race; withdrawing during competition; DNF
progress report; interim update; how things are going · in progress; ongoing; underway