@Mark JZ Yeap Thank you for reaching out to us!
1) Azure free trial account: Azure free account is available to all customers who have never tried or paid for Azure before. Starting is free, plus you get $200 credit to spend during the first 30 days and free amounts of services. Please refer to FAQ for details: https://azure.microsoft.com/en-us/free/free-account-faq/
2) Pay-as-you-go: Is another Microsoft Azure offering. With pay as you go, you only pay for the services you use at pay-as-you-go rates. Reference links: https://azure.microsoft.com/en-in/pricing/purchase-options/pay-as-you-go/ and https://azure.microsoft.com/en-in/pricing/
3) Enterprise agreement: Is an offering where you purchase Microsoft Azure services under an Enterprise Agreement (EA), Enrollment for Education Solutions (EES), Server Cloud Enrollment (SCE) or Microsoft Customer Agreement (MCA) from a Microsoft representative. As a customer or a channel partner, you're guaranteed to receive prices at or below prices shown on your Customer Price Sheet (CPS) or the price in effect on the effective date of your Azure purchase. Related to docs - https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/ea-portal-agreements and Azure EA pricing
4) Azure for student: Is a free Azure subscription for students. The student must verify their academic status through their organization's email address. More details at https://azure.microsoft.com/en-in/free/students/ and https://learn.microsoft.com/en-in/azure/education-hub/azure-dev-tools-teaching/program-faq#azure-for-students
You may also check Azure Offers URL - https://azure.microsoft.com/en-in/support/legal/offer-details/ for details about other Azure offerings.
Hope this helps!
Feel free to reply if you have additional questions that needs our attention.
If the response helped, do "Accept Answer" and up-vote it