What's the difference between Multi-Cloud and Hybrid Cloud

Multi‑cloud and hybrid‑cloud are often used synonymously, but there is in fact a difference. Various perspectives & explanations -

Microsoft - A hybrid cloud is a type of cloud computing that combines a private cloud (on-premises infrastructure), with a public cloud (computing services offered by third-party providers over the public internet). The hybrid cloud is evolving to include edge workloads. Multicloud computing refers to the use of multiple cloud computing services from more than one cloud provider (including private and public clouds), in a heterogeneous environment. 

Google - Within the context of Google Cloud, the term hybrid cloud describes a setup in which common or interconnected workloads are deployed across multiple computing environments, one based in the public cloud, and at least one being private. 

The term multi-cloud describes setups that combine at least two public cloud providers, as in the following diagram.

A multi-cloud setup might also include private computing environments.

Oracle - Hybrid cloud architecture uses both a public cloud provider, such as OCI, and on-premises infrastructure to meet enterprise IT needs. Hybrid cloud architecture is gaining importance as certain workloads cannot be moved to public cloud data centers for reasons that include data residency, network latency, and infrastructure performance requirements. Oracle Exadata Cloud@Customer combines the benefits of the public cloud with customer data centers. Multicloud is a cloud computing strategy that uses the best services from more than one cloud provider to deploy a solution. It’s typically driven by workload, business, and data governance requirements. A multicloud solution integrates IaaS, PaaS, and SaaS in a tightly or loosely coupled architecture. With Oracle Database Service for Microsoft Azure, you can deploy Oracle Database on Oracle Cloud Infrastructure (OCI) from the Microsoft Azure console. 

VMware - Hybrid Cloud is a combination of public and private clouds, usually to orchestrate a single IT solution between both. Hybrid clouds always include a private cloud and are typically managed as one entity. Multi-clouds always include more than one public cloud service, which often perform different functions. Multi-clouds do not have to include a private cloud component, but they can, in which case they can be both multi-cloud and hybrid cloud. Although every hybrid cloud can be classified as a multi-cloud by stretching the definition, not every multi-cloud is a hybrid cloud since hybrid is defined as both private and public clouds utilized in concert. 

Citrix - A multi-cloud solution may refer to the combination of software as a service (SaaS), platform as a service (PaaS) and infrastructure as a service (IaaS) models. It may also refer to the use of several private and public cloud solutions. Essentially, a hybrid cloud refers to a pairing of a private cloud and public cloud. A hybrid cloud is not a multi-cloud, though a multi-cloud may include hybridization. 

BMC - Hybrid always includes private and public, while multi-cloud always includes multiple public clouds but can also incorporate physical and virtual infrastructure (including private clouds). Unlike a multi-cloud model, in which different clouds are used for different tasks, the components of a hybrid cloud typically work together. As a result, data and processes tend to intermingle and intersect in a hybrid environment, while in a multi-cloud situation, usage typically remains in its “own” cloud’s silo.

CloudFlare - A hybrid cloud infrastructure blends two or more different types of clouds, while multi-cloud blends different clouds of the same type. You might say hybrid cloud is like combining apples and oranges, while multi-cloud is like combining different types of apples.

Nutanix - ...hybrid combines the resources of two different clouds – could be two private, two public, or a mix of both....a hybrid cloud model is also indeed a multi-cloud model. However, the inverse is not always true. A multi-cloud configuration can be hybridized but it can also exist without the need for individual clouds to talk to each other.

NGINX - In a hybrid‑cloud infrastructure, the public cloud’s role is to extend the  functionality of the private cloud or on‑prem environments. Hybrid‑cloud  infrastructures often include multiple public clouds, and therefore combine  hybrid‑cloud and multi‑cloud.