The source contrasts an "employee mindset" with an "ownership mindset" through an illustrative anecdote about a restaurant visit. An employee mindset, exemplified by a server adhering strictly to rules even if it means losing business, focuses on doing the minimum and following policies without considering broader implications. Conversely, an ownership mindset, which the speaker advocates for, involves taking initiative, seeking solutions, and prioritizing the business's success as if it were one's own, leading to increased responsibility and a proactive approach to sales and growth within any company. The speaker emphasizes that adopting this mindset is crucial for personal career advancement and overall business prosperity.