Both the Personal Gift Achievement badge and the Self Donor Milestone badge are displayed on the personal page of donors who make a donation in support of themselves for a TeamRaiser event.

The difference between the Personal Gift Achievement badge and the Self Donor Milestone badge would be in reporting. Report writer offers a TeamRaiser Milestones report that outputs data about those who have achieved a Milestone. The Personal Gift Achievement badge does not appear in the Milestones report. If your organization is going to be interested in reporting on Milestones, the Self Donor Milestone badge would be more useful than the Personal Gift Achievement badge.

Other than reporting capability, the difference between the two is purely aesthetic.