I'll take a stab at the answer.
The $25 billion is represented by CRA, and it represents the total annual value of all tax recoveries at both the federal and provincial levels across all compliance initiatives.
What's represented in the budget is a very small subset of new initiatives that would support compliance activities, for instance, in GST/HST evasion. Another example is non-resident income disclosure. Again, it is a very small subset of the larger $25 billion of collections and compliance activities at CRA on an annual basis.