Latitude doesn't, you're right, though the map on the site you linked shows broad-strokes correlation, and I've found it helpful if I guess imprecise in illustrating general temperature differences.

The difference in summers - cool summer vs hot summer - is a big one, and I'd suggest that it makes Boston's climate not really the same as most of northern Europe. We haven't traditionally needed air conditioning in Germany, for example, while I understand Boston and New England (the upper mid-Atlantic and New York, surely, when I lived and visited there) come to rely on it during the summer months to not just live in puddles of sweat.