Is saying that you will do something equivalent to saying that you promise to do something, such that not doing strictly what you said (e.g. late for 15 minutes with reasons) would be something as severe as breaking a promise?
Learn English – About “will” and “promise”
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Best Answer
The word promise generally implies a greater than usual commitment.
If you say "I'll be there at noon," then don't show up, you can later explain, "Sorry, I had to do a last-minute errand."
But if you say "I promise I'll be there at noon," you're telling someone you mean it - you WILL be there at noon. If you say "Sorry, I had to do a last-minute errand," they might reply "Why didn't you think of that before you made a promise?"