When should I use sameAs versus knowsAbout in Schema.org markup to optimize a webpage for SEO, Google AI Overviews, and semantic indexing?

Sometimes I ask ChatGPT for guidance before I answer a question. Sometimes I check myself after I’ve already answered to be sure I’m right.
I was asked about sameAs vs knowsAbout usage by one of the students in my SMX GEO Master Class.

The question:

One thing I’m a little fuzzy on is when to use sameAs and when to use knowsAbout schema.

Do I use sameAs for the main entities (main point of the page) and knowsAbout for the other entities I discuss, or am I off here?

My answer:

In short, yes.

sameAs for primary entities, and knowsAbout for related, or less salient entities.

ChatGPT’s Answer:

Use sameAs and knowsAbout in Schema.org structured data to communicate different types of relationships between a webpage and an entity (typically a person, organization, or brand). Here’s how and when to use each:

✅ sameAs: Use for Identity Equivalence

Purpose

sameAs is used to declare that the subject of the schema (Person, Organization, Brand, etc.) is the same as another entity described at an external URL (typically a social profile, Wikidata, or Wikipedia).

Use When

• You’re linking to authoritative profiles or references that define the same identity.
• Common for Google’s Knowledge Graph reconciliation.
• Ideal for linking to:
  • Wikipedia pages
  • Wikidata entities
  • LinkedIn, Facebook, Twitter, etc.
  • Crunchbase profiles
  • Author pages on other trusted sites

Example

"sameAs": [
  "https://www.inc.com/profile/search-influence",
  "https://www.linkedin.com/company/search-influence",
  "https://www.crunchbase.com/organization/search-influence"
]

✅ knowsAbout: Use for Subject-Matter Expertise

Purpose

knowsAbout expresses knowledge or expertise about a topic. It tells search engines what the subject (person or organization) knows about or is associated with in terms of skills or focus areas.

Use When

• You want to indicate topical relevance or areas of authority.
• Great for building semantic associations with services, industries, or products.
• Often used in Person, Organization, or WebPage schemas for E-E-A-T reinforcement.

Example

"knowsAbout": [
  "SEO",
  "Higher Education Marketing",
  "Local Search Optimization",
  "AI SEO",
  "Generative Engine Optimization"
]

You can also use @id links or DefinedTerm objects instead of plain text for stronger semantic context.

🔄 Key Differences

🧠 Pro Tip

In advanced implementations—especially for Person or Organization schema—use both. sameAs improves entity recognition, while knowsAbout supports topical authority in semantic SEO and AIO.

If you’d like help writing schema for your site or analyzing existing markup, feel free to share a page or markup snippet.