The teams were closer together in 14-15, when H/B were coming into seniors off the World Junior title and H/D were still dealing with Madison's recovery from hip surgery. In the seasons since, H/D have had the clear, far-and-away advantage over H/B. In their three head-to-head matchups, H/D beat H/B by 19.95 points at 2016 Nationals, 31.26 at 2017 Nationals with both teams with errors, and by 25.25 last month in Salt Lake City. H/D have made the GPF the last two seasons; H/B haven't medaled. H/D have a small medal from worlds, and without the fall in the FD, would have been on the podium. H/B haven't been yet. H/D regularly trade placements with teams that have been on the world podium. The exceptions are V/M and P/C, and they got pretty close to P/C in the SD at worlds last year. H/B are not beating teams that finish in the top 10 at worlds. H/D are considered contenders for the bronze in February.
As far as Skate Canada this weekend, H/D could very well beat W/P for silver. H/B are looking at fourth at the very highest.
This is more about results than differences. Clearly judges right now favor H/D.
Since moving to Montreal, H/D have thoroughly embraced its style: long lines, (predominately) romantic themes skated to (predominately) contemporary music (with an emphasis on
melody), a shift to a more contemporary dance style. H/D have a particular problem with skating to the melody, rather than the rhythm. I thought it very clever of their coaches and choreographers to remove this temptation in the SD (always their weaker of the two portions of the competition) by having them skate to what is essentially a rhythm track. They also have a marvelous connection with each other, a more palpable sexual chemistry than H/B, something their dance creators have also exploited (some might argue, ruthlessly).
H/B are, in some key respects, a throwback to a more classic British ballroom style. It's no surprise they won their world junior title by having a commanding lead after the SD. They are a relatively small team who skate big and with speed. They also, Baker in particular, have marvelous depth and control of edges, better knees, and a much stronger sense of rhythm than H/D. They also have a strong chemistry with each other, but it's far more romantic and playful to me than palpably sexual. In some ways, they're like the ingenue couple in a traditional musical. They also have less experience together as a team than H/D--and it takes considerable time for any dance team to gel.
Both teams have problems with lifts and twizzles. Both are relatively equal sized (in relation to each other), so developing lifts has apparently been challenging (with the result that both teams have recycled lifts throughout their careers). Both teams appear to be prone to nerves--which leads to mistakes particularly with twizzles.
Size does count in paired skating. H/D have a bigger presence on the ice because of it. And I'm not sure yet if H/B have fully developed a signature style, though they're getting closer to it.
YMMV of course.