As adjectives the difference between burdensome and imposing
is that burdensome is of or like a burden; arduous or demanding while imposing is magnificent and impressive because of appearance, size, stateliness or dignity.
As adjectives the difference between irksome and burdensome
is that irksome is disagreeable or troublesome by reason of long continuance or repetition; bothersome; annoying; irritating; wearisome; tedious while burdensome is of or like a burden; arduous or demanding.