Yeah, it's extremely difficult to tell the exact species of buteo in many cases, mostly because there are a lot of interspecies variations, based on age and other things.
Where exactly do you live? If you're in America (like I suppose), then it's not the common buzzard then (it's an Old Word Buteo IIRC). In America, buteos are hawks, in Europe/Asia, they are buzzards. Red tailed hawk would be the most obvious possibility (since, IIRC, it
is the most numerous species of buteo genus in North America, but it could also be something like a broad-winged hawk...

Oh, and to Mika's credit, eagles are much closer to buteonine hawks than buteo hawks are to falcons.

And what comes to actual naming schemes of these daytime birds of prey and how they correspond to Finnish language:
Haukka (hawk) is pretty much an umbrella term in Finnish, often used to describe almost all smaller-than-eagle daytime birds of prey (or raptors, if you wish). Falcon corresponds roughly to Finnish term "jalohaukka" (noble hawk) (but not quite! explanation further...), and their most notable feature is pointed wingtips and relatively small size. Although, in English, I believe there's much bigger difference between hawk and falcon (and kestrel and hobby and merlin and harriers and osprey...).
Which are, of course, the following:
Hawk (haukka)
Kestrel (tuulihaukka -> wind hawk)
Hobby (nuolihaukka -> arrow hawk)
Merlin (ampuhaukka -> shooting hawk)
Falcon (jalohaukka, all the rest of the members of
Falconidae - including Peregrine falcon)
Peregrine (muuttohaukka -> moving hawk)
Harriers (suohaukat -> swamp hawks)
Osprey (sääksi or kalasääski... sääksi is "osprey", kalasääski is literally "fish mosquito")
The taxonomy of raptors is a bit of a mess, you can go and check it out from
Falconiformes wiki article...