Explanation
The available purchase models are:
Pay As You Go (PAYG):Billed in arrears based on consumption. Recommended for organizations who are trying new services, rapid prototyping, or for elastic scaling.
Monthly Flex:Billed in advance with a 12-month minimum. Use monthly or forfeit that month's credits.Recommended for customers with predictable production workloads or large long-running applications, such as HR, payroll, analytics, and more.Monthly Flex maximizes cost reduction with predictable monthly spend, similar to your monthly phone plan. Delivers faster time to market by offering customers the choice of using any IaaS and PaaS services.
Oracle's current PaaS offering is "license-included PaaS." It includes:
* Compute and compute support
* Automation
* License entitlement and license support
Bring your own license
BYOL stands for "bring your own license." Previously, you could bring your own licenses to Oracle IaaS, but to get the benefits of PaaS automation, you couldn't leverage existing licenses. This has been changed. We're offering Oracle BYOL to PaaS, enabling our customers to leverage their investment in existing on-premises licenses in their journey to the cloud.
Oracle BYOL to PaaS includes:
* Compute and compute support
* Automation
* Customers bring their on-premises license entitlement and get license support via their existing on-premises support contract.
* As customers leverage their existing on-premises license entitlement, they can move to the cloud at a lower cost.

Explanation
Exadata DB systems allow you to leverage the power of Exadata within the Oracle Cloud Infrastructure. An Exadata DB system consists of a base system, quarter rack, half rack, or full rack of compute nodes and storage servers, tied together by a high-speed, low-latency InfiniBand network and intelligent Exadata software. You can configure automatic backups, optimize for different workloads, and scale up the system to meet increased demands.
Oracle now offers the Zero Downtime Migration service, a quick and easy way to move on-premises Oracle Databases and Oracle Cloud Infrastructure Classic databases to Oracle Cloud Infrastructure. You can migrate databases to the following types of Oracle Cloud Infrastructure systems: Exadata, Exadata Cloud@Customer, bare metal, and virtual machine.
Zero Downtime Migration leverages Oracle Active Data Guard to create a standby instance of your database in an Oracle Cloud Infrastructure system. You switch over only when you are ready, and your source database remains available as a standby. Use the Zero Downtime Migration service to migrate databases individually or at the fleet level. See Move to Oracle Cloud Using Zero Downtime Migration for more information.