Salesforce CPQ: Contract from Opportunity or from Order?

In order to generate a Contract in Salesforce, you either select the "Contract" checkbox on the Opportunity record or the "Contract" checkbox on the Order record. 

You shouldn't create Contracts from both the Opportunity and the Order. It is best practice to generate Contracts from the Order if you are actually using orders.

Let's check what is happening at the field level on two different contracts created via these two methods. 

So, we created two identical opportunities with two identical quotes. Then we contracted from the Opportunity for one scenario, and for the other, we contracted from the Order.

 Contract from Opportunity

Start Date and End Date on the Contract are inherited from the Primary Quote's corresponding fields. By default, the Start Date and End Date on the Subscription record are inherited from the Quote Line Group. If these dates are null, then it goes to the Quote Line level. If the Quote Line's dates are also null, then these values are set from the Effective Start Date and Effective End Date fields.

Effective Start Date is inherited from the Quote Line Group. If there is no set value on the Quote Line, it will get inherited directly from the Parent Quote unless it is set on the Quote Line itself. Ditto for the End Date, except for Evergreen Subscriptions - these get a null value for the End Date.

 Contract from Order

Start Date on the Contract is inherited from the Order's Start Date field.

Contract End Date is inherited from the shared End Date of the Order Products on that Contract. (By default, Salesforce CPQ creates a Contract for each group of Subscription Order Products with matching end dates). Start Date and End Date on the Subscription record are inherited from the related Order Product's Start Date and End Date. Note that you can "adjust the Order Contracting Method fields on the order and order products to control how Salesforce CPQ distributes subscription products on your contracts."

Also, it's worth noting that in this scenario, the Subscription field on each of your Order Products is populated with the lookup to the related Subscription record, and the subscription record is populated with the Order Product from which it originated.

When creating Contracts from Orders, you should respect the following:

 There should be at least one Subscription Order Product on the Order.

 All Subscription Order Products are activated.

 The related Opportunity hasn't been contracted yet for the Quote related to the Order (first, you should create the Order, then the Contract).

 Order Products must be related to the Quote Line of the Quote from which the Order was generated.

Whereas, in order to create Contracts from the Opportunity, two requirements must be met:

 There should be at least one Quote Line with the Subscription Pricing field set to "Fixed Price" or "Percent of Total" on the Primary Quote.

 You must define the Start Date either on the Primary Quote, Quote Line Group, or the Quote Line itself (it is recommended to set the Start Date directly on the Quote. This way, it is guaranteed that all lines get a Start Date).