A normal change needs to follow the entire change process; it should be scheduled, have its risk assessed, and be authorized. Normal changes include both minor (low to medium impact and urgency) and major changes (high impact and urgency). All changes that aren't standard or emergency ones should be treated as normal changes and adhere to the change process.
Example: Moving on-premises services to the cloud
Standard changes on the other hand are preapproved changes that are low-impact, well-known, and documented. Standard changes require a risk assessment and authorization when implemented for the first time, but subsequent implementations can be done without these precautions as long as the change hasn't been modified.
Example: Replacing a printer's ink cartridge