What's The Difference Between The Order Form Submitted And Order Submitted Triggers?

Order Form Submitted Trigger

The Order Form Submitted Trigger was created back when workflows first launched.

Can be used to target when the 1st step of a 2-step order form has been submitted with just the contact details (ex. abandoned cart sequence).
Works with the Facebook Conversions API action in workflows.

The Order Submitted Trigger is newer and:

Only runs upon a full purchase submission - when using a 2-step order form, this trigger can only be fired once the 2nd step has been submitted with the card/payment details to complete the order.
Does not run multiple times on multiple product purchases, even if multiple are purchased at one time.
- It contains a single checkout object that sends info only a single time upon an order form submission, even if that one order session consists of multiple products bought.
Does not work with the Facebook Conversions API action in workflows. (Doing so will lead to a 'skipped due to' → No attribution data available with this input trigger." error message.)
Provides the ability to filter the trigger directly on the basis of the global product/price. The Order Form Submitted Trigger does not provide this functionality, it requires you to filter on a per funnel or per website basis.
Enables the ability to use order-related Custom Values inside the workflow. These include Custom Values related to the customer, order details, coupon information, and payment gateway.
Enables you to use conditions related to order details or product details in If/Else branches to direct the workflow based on the cart value/products purchased/funnel the sale happened in.