待つ and 待機: waiting for something and standing by
Compare waiting for a friend’s arrival with a request to stand by for instructions, keeping readiness separate from completed work.
Waiting for an arrival or event
待つ, read まつ, means waiting for someone to arrive or something to happen. 友達が来るまで、ここで待ちます。 says that the person will wait here until the friend arrives.
結果を待っています。 says that the person is waiting for the result. It does not report that the result is already available or has been checked.
Being ready to act when needed
待機, read たいき, means standing by, ready for a needed action. 指示があるまで待機してください。 asks the person to stand by until instructions are given.
係員は入口で待機しています。 says that an attendant is standing by at the entrance. 入口で supplies the location; 待機 does not itself name a particular place.
What is awaited and what is complete
次の作業に備えて待機しています。 says that the person is standing by in readiness for the next task. It does not report completing that task.
友達を待ちながら本を読みました。 says that a book was read while waiting for a friend. Waiting does not require doing nothing else.
Does 次の作業に備えて待機しています。 report that the next task has also been completed?
Show the answer and why
No. It describes a current state of readiness for the next task. Completion of that task is not reported.