I’m an old engineer, but here is my perspective:

Marketing is the money you spend to acquire potential customers. Potential is the key word. How is this done? Think of the word “attraction.”

Sales is the money you spend to close a sale. How is this done? Think “persuasion.” Sales is about doing whatever is necessary to make a transaction happen.

Examples:

Sign on building: marketing

Brochures: marketing

Advertisements: marketing

—————-

Pitch or proposal: sales

Working with a customer: sales

Site Visit: sales

I usually account for marketing expenses as “operations or overhead costs” and sales as “COGS or direct cost.” It just makes more sense to me that way, and it ties the sales cost to gross margin so it is very “visible.”