Flow vs Logic Apps vs Functions vs Webjobs

Azure Functions or WebJobs
All these services are useful when "gluing" together disparate systems. They can all define

• input
• actions
• conditions
• output

You can run each of them on a schedule or trigger. However, each service has unique advantages, and comparing them is not a question of "Which service is the best?" but one of "Which service is best suited for this situation?" Often, a combination of these services is the best way to rapidly build a scalable, full-featured integration solution.

Flow vs. Logic Apps
Microsoft Flow and Azure Logic Apps are both configuration-first integration services. They make it easy to build processes and workflows and integrate with various SaaS and enterprise applications.

• Flow is built on top of Logic Apps
• They have the same workflow designer
• Connectors that work in one can also work in the other
• Flow empowers any office worker to perform simple integrations (for example, get SMS for important emails) without going through developers or IT. Flow is for Office workers and business users  as a self service tool.

On the other hand, Logic Apps can enable advanced or mission-critical integrations (for example, B2B processes) where enterprise-level DevOps and security practices are required. It is typical for a business workflow to grow in complexity over time. Accordingly, you can start with a flow at first, then convert it to a logic app as needed. Logic apps are for IT pros and developers used for mission critical operations.

Functions vs. WebJobs
Azure Functions and Azure App Service WebJobs are both code-first integration services and designed for developers. They enable you to run a script or a piece of code in response to various events, such as new Storage Blobs or a WebHook request. Here are their similarities:

• Both are built on Azure App Service and enjoy features such as source control, authentication, and monitoring.
• Both are developer-focused services.
• Both support standard scripting and programming languages.
• Both have NuGet and NPM support.

Functions is the natural evolution of WebJobs in that it takes the best things about WebJobs and improves upon them.

The improvements include:

• Streamlined dev, test, and run of code, directly in the browser.
• Built-in integration with more Azure services and 3rd-party services like GitHub WebHooks.
• Pay-per-use, no need to pay for an App Service plan.
• Automatic, dynamic scaling.
• For existing customers of App Service, running on App Service plan still possible (to take advantage of under-utilized resources).
• Integration with Logic Apps.

Functions support in-browser editing where as web jobs doesn't support in browser editing.

Both can be invoked by Event Triggers and Timer based Scheduling. We can make web jobs as continuous.
Functions support more event triggers than Webjobs , Functions support

• Timer
• Azure Cosmos DB
• Azure Event Hubs
• HTTP/WebHook (GitHub, Slack)
• Azure App Service Mobile Apps
• Azure Notification Hubs
• Azure Service Bus
• Azure Storage

Webjobs support

• Azure Storage
• Azure Service Bus

Flow vs. Logic Apps vs. Functions
Which service is best suited to you depends on your situation. For simple business optimization, use Flow.If your integration scenario is too advanced for Flow, or you need DevOps capabilities and security compliances, then use Logic Apps.
If a step in your integration scenario requires highly custom transformation or specialized code, then write a function and trigger the function as an action in your logic app.

You can call a logic app in a flow. You can also call a function in a logic app, and a logic app in a function. The integration between Flow, Logic Apps, and Functions continues to improve over time. You can build something in one service and use it in the other services. Therefore, any investment you make in these three technologies is worthwhile.