I've used Zapier a fair amount and I wrote an article about Airflow so I have a fairly good understanding of that too. I would never really consider them alternatives though? To me Zapier is a low/no code tool that offers a bazillion integrations and Airflow is a workflow orchestration tool. So comparing to both of them confuses me and I guess choosing one would give you a more nieche audience but one that you can co…
As of now these are the broad categories that abuse the term workflow.
1. State Machines
For example in Jira a bug/ticket moves through different states to reach a final stage. This type of state-machines can be found in a lot of different softwares - most CMS/bug-trackers/CRMs where the entity is different (document/bug/lead).
The motive of these systems who call themselves as workflow engines - is to provide a structure to an otherwise ad-hoc movement of entities so that a lead/manager is able to ensure a process and collect statistics.
2. Automations
For example "apple workflow" app or Zapier or Zoho Flow. These softwares define a sequence of steps that are triggered when an event occurs in the system.
The motive of these systems are to enable automation and integrations between different software components with zero code (thus, no-code).
3. Process Designers (Bad term but can't think of anything better at the moment)
For example Airflow/Camunda. These systems are not necessarily low-code but they mostly deal with arranging individual components of code such that a process can be assembled as quickly as possible. These systems usually are accompanied by a visual designer like what Zapier has, but the intentions are mostly to ease out the process, than being a complete no-code tool to create automations. However, their marketing tries to sell themselves as no-code platform for business folks.
The motive is not yet very clear to me but from my initial intuition they can be used to initiate some data-processing pipeline, I guess? If anybody can throw more clarity, please leave a reply.
Now as you can see, much like how a "Process" can mean many things in many different context, the term "Workflow" can mean a lot depending on the context. Any software that calls itself the ultimate workflow solution is just a lie. It's like calling something an "ultimate process engine" - doesn't make sense.