Yes, they're similar.
Explanation:
Triangles are similar when they have the same shape but vary in sizes. This is our case here. We have two equilateral ∆s which makes them similar but what differs them is the length. One is 6 and the other is 10. Although that doesn't affect anything in the triangle. If you drew a height to any base (in either triangle) it would still be a bisector, median, and perp bisector. Their angles are alsp equal.