The Lead Gen & CRM Ads tracking tag will not track as many users as your Google Analytics tag will, for various reasons.
Example: An audience in your Lead Gen & CRM Ads account shows we cookied 10 unique visitors yesterday. Meanwhile, in Google Analytics, you're seeing 15 unique visitors to your site yesterday.
This is not uncommon! Our stats only measure the number of unique people who we cookie. That rules out a lot of users. The questions to ask are:
What % of your traffic is non-desktop? (We only cookie desktop browser visitors)
What % of your traffic is using Safari? (Safari blocks 3rd party cookies)
What % of your traffic is running AdBlock?
What % of your traffic is blocking cookies?
In addition, we don't count users we've already cookied. If the same person comes to your site three days in a row, your analytics might display that as one visit each day. We would only count that user one time since we cookied them the first day they visited your site.
When you correct for these things, we find that Google Analytics numbers tend to line up fairly well with what we're showing.