Comparing Documents & Sources
Use AI to find differences, contradictions, and gaps across multiple documents.
Comparing Documents & Sources
One document is information. Two documents are intelligence. AI excels at comparing texts to find agreements, contradictions, and gaps -- the kind of analysis that takes a human hours of careful cross-referencing.
Triangulation -- checking a claim across three independent sources -- is the gold standard for verifying information. If all three sources agree, the claim is likely reliable. If only one source makes a claim, it needs verification. AI makes triangulation practical instead of theoretical.
Side-by-Side Comparison
The Basic Compare Prompt
"Compare these two documents on [topic]:
- Where do they agree?
- Where do they disagree or contradict each other?
- What does Document A cover that Document B doesn't?
- What does Document B cover that Document A doesn't?
- Which is more thorough/credible?
Document A: [paste]
Document B: [paste]"
Version Comparison
When comparing drafts or revisions:
"Compare Version 1 and Version 2 of this document:
- What was added in V2?
- What was removed from V1?
- What was changed (show before and after)?
- Are there any changes that alter the meaning significantly?
- Rate the overall improvement: better, worse, or lateral move?
Version 1: [paste]
Version 2: [paste]"
Multi-Source Analysis
Triangulating Information
"I have information about [topic] from three different sources. Compare them and:
1. Identify claims all three agree on (likely reliable)
2. Identify claims only one source makes (needs verification)
3. Identify contradictions between sources
4. Assess overall: which source is most credible and why?
Source 1 (Name/Type): [paste]
Source 2 (Name/Type): [paste]
Source 3 (Name/Type): [paste]"
Competitor Analysis
"Compare these two competitor products/services:
- Feature comparison (table format)
- Pricing differences
- Target audience differences
- Unique selling points of each
- Weaknesses of each
- Overall recommendation for [your specific use case]"
When comparing vendor proposals or product options, always include your specific use case and priorities in the prompt. Without context, AI will give you a generic comparison. With context -- "we are a 10-person team focused on speed over features" -- the comparison becomes a recommendation tailored to your situation.
Due Diligence Applications
Proposal Comparison
"I received proposals from three vendors. Compare them on:
1. Scope of work (what's included/excluded)
2. Pricing (total cost, payment terms, hidden costs)
3. Timeline (start date, milestones, completion)
4. Team/qualifications
5. Risk (what could go wrong with each?)
6. Value for money ranking
Format as a comparison table, then give your recommendation."
Contract Review
"Compare this contract to a standard [contract type]. Flag:
- Clauses that are missing
- Terms that are unusually favorable to one party
- Ambiguous language that could cause disputes
- Anything I should negotiate before signing"
Tips for Better Comparisons
- Label your documents clearly -- "Q1 Report" vs "Q2 Report" or "Vendor A Proposal" vs "Vendor B Proposal"
- Specify what matters -- "Focus the comparison on cost and timeline" if those are your decision criteria
- Ask for a recommendation -- Don't just compare; ask AI to recommend based on your priorities
- Check for missing context -- "What information would you need to make a better comparison?"
AI comparisons are only as good as the documents you provide. If one vendor's proposal is detailed and another's is vague, AI will naturally favor the detailed one -- even if the vague one is the better choice. Always consider whether differences in the comparison reflect real differences or just differences in how thoroughly each party wrote their document.
Exercises
0/3Find two articles or reports on the same topic from different sources. Use the triangulation prompt to compare them. What contradictions or gaps does AI find?
Hint: News articles work great for this -- find two outlets covering the same story and compare their coverage, emphasis, and conclusions.
When comparing three sources, a claim made by only one source should be:
Describe a situation at work where comparing documents would save you time or improve a decision. What documents would you compare, and what would you look for?
Hint: Think about vendor proposals, contract versions, policy updates, competitor analysis, or quarterly reports.