If you're at the store, look at the "32X" military toys made by the same company that makes the 1:18 scale military toys (21st Century Toys). Check Wal-Mart near the hot wheels and stuff. 32X is 1:32 scale, so it and 1:35 are fairly close... If you're wanting a comparison.
1:18's quite a ways bigger. 1:18, if you're doing a figure of average height, would be about 4" tall, or "6 foot to-scale" in 1:18 scale. (IE: 4" = 6' tall). So 3.75" is close and matches up well enough... You'll notice though if you compared 21st Century Toys, BBI, or Forces of Valor figures to a Star Wars figure of average height, that usually the SW figure is a hair shorter.
Jesse, you're correct... However, the little unleashed are still a bit bigger. I think Legos are probably a little closer (the mini figures) in scale, actually.
Like I said, if you guys have the 32X toys from 21st Century Toys around, they're pretty close... 1:35 and 1:32 are very popular military collecting/modeling scales, so I understand why they went with those scales for this diorama thing. Pretty slick looking, but one more thing I don't need to buy, so I guess I'll avoid it.