つもりだ

1.「つもりだ」indicates the speaker's intention or plan. This intention has been thought out beforehand, rather than being a spontaneous decision. This is also the difference between 「つもりだ」and「ようと思う」. On the other hand,「予定だ」differs from the previous two in that it describes a schedule, a pre-decided plan, rather than just the speaker's intention.
Note:
- This structure is only used to talk about the speaker's intention, not the intention of a third person.
- Do not use this structure if you simply want to ask about the listener's intention, especially with someone in a higher position. Only use「つもりだ」when wanting to confirm the listener's determination, when they intend to do something that we find hard to understand. The question at this time will imply suspicion, dissatisfaction, criticism...
Example: 腐りかけているのに、食べるつもりですか。(Even though it's starting to rot, you still plan to eat it?) Usually, people won't eat food that's gone bad, yet the listener plans to. The speaker doesn't understand this, so they ask.

2. 「つもりだ」expresses the speaker's belief or assumption that things are a certain way, while in reality, they might not be, or others may not think so.