Different varieties also have differently-shaped leaves and cones, so you might be able to identify hop variety by sight. For example, the more modern high alpha varieties tend to have big, long cones and slightly longer leaves while the traditional noble varieties tend to have smaller, rounder cones and shorter, broader leaves.
In addition to doing the rub and sniff test, you can also taste the hops and/or make a hop tea to get a sense of bittering potential and character.
Finally, be aware that there are male hop plants which do no bear cones (and can reduce yield of nearby female plants by making them produce seeds in addition to alpha acids), and blasphemous and evil varieties of hops which are grown for purely decorative purposes. The latter might not produce cones at all, and the cones they do produce contain little to no alpha acid. You might be un-bitterly disappointed.
I'd discreetly ask your neighbor if the hops bore cones in previous years and/or if he bought the house from a homebrewer. Be prepared to adjust your beer-trading agreement accordingly.