DSfW was created to emulate an AD environment, as such, AD utilities are the designed method of manipulating the AD environment, including the creation of users. Microsoft MMC | Active Directory Users and Computers(ADUC) is the recommended approach for creating and managing users in a DSfW domain. Using iManager may leave out certain attributes used by AD.
This Knowledge Article provides some information on the Display Name attribute, which is missing if using iManager instead of ADUC:
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