Both games have different feeling and goals, so being better only subject to personal preference. I like the realistic visuals and excellent details DC is putting into it with less number of cars and reasonable tracks along with arcade/simulation feeling and giving control over the game completely on choosing time, weather etc., for a racer. And FH2 is packing content but going away from being realistic to arcade racer with exploration and also has less details compared to DC. I'm sure everyone gonna realize that DC is looking way better and realistic in Visuals than FH2(it has content to explore which DC going to lack much) after E3 because of PS4 being powerful and closed circuilts than FH2.

in Short, FH2 is arcade feeling with exploration in Open world with good visuals/details and more content , whereas DC is realistic aracade/simulation feeling with beautiful vistuals, excellent details and competitive club challenges across everything in closed circuits .

Actually Horizon 2 will be a lot less arcady then the first game its already been confirmed that every cars will feature full tuning which wasn't in the first game you could upgrade the cars with new parts but none of them where tuneable.  Plus Horizon 2 will be a much longer game its already been confirmed that the single player mode will feautre 700 hundred races and will take at least 100 hours to complete the first games single player mode could be completed in about 20 hours.  Also with 200+ cars Horizon 2 will pretty much have every car featured in DriveClub plus a ton more.

DC choose less cars because they went with giving cars more details with authentic feeling and being close to the real cars in visuals, audio, their internal features etc., for handling which is not going to be there in FH2. Like i said before FH2 has content but not going be a realistic racer like DC and also the enviroments as well where DC trying to match them close to the real world with visuals and excellent details and proving a little arcade feeling with some content and being more close to realistic simulation of social gaming with club challenges,  but FH2 gives them different coloring for the visuals instead of being realitic for their goal of open world explore. Dont forget that PS4 is powerful and both games being same resolution and FPS so we can easliy expect better visuals in DC because of closed circuts and differnet goals. 

Horizon will actually have a much bigger social aspect then DC.  Plus on top of that it will feature excellent music like the first game.  Also as far as the sounds of the cars go Forza has always been top notch in that department, not that it matters that much for Horizon since it will also feature a killer list of songs on 6 different radio stations.  Also DC will not have anything close to the real world since none of the tracks in the game will be actual real world tracks.  If you want a real world feel then stick to racing games that have real tracks or tracks that are based on real world locations like the main Forza games, GT, PGR, or Project CARS or other sim racers that feature real tracks.

Well DriveClub is close to being finished now I doubt they could easily add dynamic weather unless they plan to delay it a couple of month more.

The last time that one of the developers from evolution studios visited our university, he said that drive club is an arcade racer which will compete with the likes of forza horizon.

just for your information.

the fact that it is not an open world game, nor a simulation has nothing to do with the ps4. its a developers decision.
the other fact, that it has less cars and content is most likely due to less licences and less 3D artists / slower 3D artists / worse working environment / quality over quantity.

for the guys trying to compare graphics at this stage: graphics are more dependent from the developers work than raw graphical computing power. higher raw power is not automatically better visuals. forza horizon 2 will definitely aim for realistic graphics. read this article, it has some tech information too: http://www.forzamotorsport.net/en-us/news/Forza_Horizon_2_IGN_Announce . anyway, since it is an open world game, you can expect the environment to be clearly lower poly than the main racing-road and cars.

At this point Playground Games has close to 200 employees not sure how many Evolution Studios has but probably a fair amount less its probably one of the main reason the game was delayed for a while since they didn't have enough manpower to finish it in time for the original release date.  Also like said before Horizon 2 will be much less of an arcade game then the first title since all the cars now feature full tuning and the its based on Forza 5.  The 360 version on the other hand will probably have just as much of a arcade feel as the first game since its base game is the first title.