1. Note that most “Modern Orthodox” (a.k.a. “Religious zionists”) are cousins of the Hareidim, especially the leading rabbanim of each movement.
2. They learn from the same sefarim.
3. Compared to the goyim, they dress alike (don’t believe: take the typical American/Israeli shiksa/hiloni and compare her to a Boro Park girl or a modern suburban orthodox girl or even a Williamsburg/Bnei Brak girl). It’s the shiksa/hiloni who stands out.
4. The underlying ideological differences pertain to events that happened 70+ years ago, and you need to be a historian to understand. In terms of modern issues, there isn’t much difference anymore (there are both Hareidi and modern doves, and a lot more hawks on both sides; they are support Keynesian stimulii with little concern for paying for it; opposition to abortion and support for large families is the rule among both).
The goyim have a phrase “making a mountain out of a molehill”. The Hareidi/modern differences may be colorful, but they are a molehill. The difference between the Shomer Mitsvos and the Hilonim is the mountain, which is rapidly growing.