Both applications handle standard Boolean union, intersection and difference. The implementation is slightly different in terms of interface, each one having its pros and cons. In the end, results are very similar.

In Bryce, you get several types of rocks including shingles and others; the type of rock is selected at random. In Vue, you only get one type of rock, but with subtle variations in color.

I've always found that Bryce rocks look pretty crude. Anything larger than a pebble will look bad in a scene. Vue rocks are quite a bit more detailed, and can actually be used for reasonably sized rocks/stones.

I find that Bryce plants don't look too good when seen from a distance, but look much better up close. In Vue, it's the opposite. Plants really look terrific from a distance, but maybe not quite as good up close (at least for trees).

In Bryce, you can use the Tree Lab to create entirely new types of trees. Sadly, you're limited to trees, though. You cannot create small plants (but you can possibly trick the Tree Lab into producing something shrub-like). Also, I find that achieving really nice trees in the Tree Lab is not straightforward, to say the least (and the Tree Lab is also prone to hang-ups).

Vue has 30 different plants in it. That includes all sorts of plants, ranging from grass and weeds to full blown trees. You cannot edit the plants (although I've read some very interesting tutorials on how you can create different types of plants in Vue). But the really great thing with Vue is that each time you create a plant of a given species, it is grown different from the others. It's really nice when you want to create groups of plants, because each plant in the group will look akin, but different. Also, there are very subtle variations in the colors of the plants; this makes a great difference in terms of realism. Last but not least, Vue renders the vegetation very rapidly.

I think Vue has the edge on vegetation.

Both applications produce very nice terrains, and are also capable of handling symmetrical lattices/terrains. Bryce has slightly more effects, whereas Vue lets you sculpt the terrains in real-time 3D.

Vue offers a set of buttons to quickly create predefined terrain styles, including iceberg and an interesting "Lunar" terrain.

Bryce has dozens of filters to edit the terrains, some of which produce really amazing results. The "Erode" effect is particularly fast and realistic. Vue offers 4 different types of erosion, and lets you select the softness of the rock, which actually has an effect on the way erosion performs. I still have a preference for Bryce's erosion.

Filtering terrain altitudes and importing data is very similar in both applications.

Bryce terrains are always square; Vue terrains can be any size.

Bryce lets you use a number of predefined "fractal procedures" to create new terrains. Vue hides a similar option in the rather remote "Add function to terrain" dialog. This dialog also lets you create terrains from various fractal procedures; you can create entirely new procedures (Vue's functions) for amazing results.

In terms of terrain modeling, I think Bryce has the edge, mostly thanks to the "Erode" option.

Bryce's Metaballs sadly have no equivalent in Vue. You can create very nice, organic looking objects using metaballs, but the rendering time of these objects is horrendous.

Bryce offers slightly more options in this respect, although the most important one, which is Snap to land/Drop is available in Vue. Snapping also seems to be more precise in Bryce.

Again, the options are very similar in both applications. Vue seems to offer slightly more control over object dispersion (scatter). When replicating, Bryce lets you scale the translation with the size of the objects.