How their Performance Max approaches align and diverge

Performance Max (PMax) campaigns have become the cornerstone of AI-driven advertising. 

Both Google and Microsoft offer advertisers a way to consolidate creative assets, audience signals, and automation into a single campaign type. (Disclosure: I work as Microsoft’s product liaison.)

While the concept is similar across platforms, the execution and feature sets differ significantly.

This article aims to provide an objective comparison of Google PMax and Microsoft PMax as of late 2025. 

We’ll explore what’s universally true, what’s unique to each platform, and strategic considerations for advertisers looking to maximize performance.

What’s universally true about PMax

Despite platform differences, several foundational principles apply to PMax campaigns across both Google and Microsoft:

Asset groups replace ad groups

PMax campaigns use asset groups instead of ad groups. 

Each asset group contains a mix of creatives (images, headlines, videos where applicable) and audience signals. 

Unlike ad groups, asset groups do not carry inherent prioritization. 

Budget allocation is at the campaign level, so if you create multiple asset groups, expect the system to distribute spend algorithmically rather than based on your preferences. 

Tip: If you want to prioritize certain creative or audience segments, create separate campaigns rather than relying on asset groups.

Automation and conversion requirements

PMax is designed for automation. Both platforms require you to use Maximize Conversions or Maximize Conversion Value bidding strategies. 

This means you must have conversion tracking in place. Ideally, you should achieve at least 30 conversions within a 30-day period to ensure stable performance. 

Major changes, such as bid strategy shifts or prolonged pauses, trigger learning periods that can temporarily impact results.

Goal alignment matters

PMax works best when your goals reflect reality. 

Setting an artificially low ROAS target will not guarantee more volume; it will guarantee lower ROAS. 

Align your budgets and bidding strategies with actual business objectives to avoid performance volatility.

Search term visibility and negatives

Both platforms provide search term insights from keywordless technology and search themes. 

• Google PMax supports negative keywords broadly, allowing up to 10,000 negatives per campaign. 
• Microsoft PMax’s self-serve negative keyword support is still in pilot as of Q4 2025.  

Advertisers can chat with support to have negatives added to their campaigns until the full roll-out of the pilot.

Ad rank and AI placements

PMax campaigns compete based on ad rank, just like traditional search campaigns.

Both platforms unlock AI-driven placements, but Microsoft has had these live longer and reports strong performance.

If AI surfaces are a priority, PMax is the campaign type to lean into.

What’s true for Google…