Which do you use and when?
Here's my take.
Marketing nurture should be used for prospects that have low / no ICP fit, aren't owned by anyone in sales, and should be tailored to at least one known characteristic of the prospect. Such as problem, use case, industry, or buyer type.
Sales sequences should be used when the prospect is owned by someone in sales, should be customized to each recipient based on known information about them, and should never be set it and forget it.
Sales sequences should never take a spray and pray approach.
Here's another important thing.
No matter if it's marketing nurture or sales sequences, every email sent should come from a real person and have a real reply to address.
Each email should be written in a conversational style and adapt the brand tone and voice. Emails should be short and to the point and add value directly in the email.
Sequences should try for a reply, nurtures should try and get a click.
Having a strong operating process between marketing and sales for both types of communication is essential. Appoint to responsible individuals and include your revops resource.
Otherwise you're leaving the communication with your most important audiences to chance.