Spinet Piano - 36" - 37 1/2" tall
The spinet piano is desired because of its lighter weight, smaller size, and generally smaller price tag. This piano can be an excellent starter piano if well constructed.
The drawback to the spinet is that it has less soundboard area than taller pianos, shorter bass string length, and because of the recessed action can be harder to service.
Console Piano - 40" - 43" tall
The console piano has greater soundboard area than the spinet, longer speaking bass string length, and an easily accessible action for repair.
The console usually has a direct action which is operated directly by the keys unlike the recessed spinet action. However the actions must also be smaller in size from the spinet in order to accomodate the limited space from the back of the keys to the strike point of the hammers. This will sacrifice some performance standards like repetition.
The black legless style shown is common to Asian pianos with black or white polyester finishes. It can also be found in wood finishes.
Studio piano - 44" - 50" tall
This piano is the best of both worlds. It is large enough to have as much soundboard area as a small grand piano, a full sized action, and the plus of braced legs and ball-bearing casters. This style is often used by schools, churches, and music teachers for its great performance. This is an excellent size for more advanced students who can't afford or don't have the space for a grand piano.
Professional Studio - 52" tall
It is becoming popular again to produce new pianos that are the height of pianos found from the turn of the century oftern called Cabinet Grands. The performace standards of the new professional studio pianos is very high and the tone production rivals a fair sized grand because of the tremendous soundboard area and very long speaking length of the bass strings.
This piano is truly the ultimate vertical for those who want the grand piano sound in a vertical piano.
The Cabinet Grand - Vertical Grand - Upright - usually 52" high
Here is the turn of the century vertical grand piano. It doesn't matter what you call it, it certainly is formidable in nature with many still in existance at over a hundred years old. It is wonderful that these pianos have lasted as long as they have and still grace us today with unparalled woodworking craftsmanship.
These pianos can often be completely restored to their original elegance and beyond by very talented piano rebuilders. However, the cost of restoration can be significant and one must seek out the best rebuilders before purchasing an instrument like this particularly if it is going to be used by a piano student in the course of serious lessons.
In a unrepaired state, a piano like this should be carefully evaluated by a qualified piano technician prior to purchase.
Grand Piano - 4'6" - 9' length
By style, a grand piano is a grand piano. Terms like Baby Grand, Parlor Grand, Petite Grand, etc do not necessarily mean the same sizes throughout the industry and they come in an unbelievable number of quality grades as well. This means that you can buy a 5' 8" grand piano in an economy construction version or an ultimate construction version which will cost much more. Make sure when buying that you are comparing the level of quality between the instruments you want to purchase.
World class grand pianos have so earned their names because of their construction excellence, years of performance on stage in all venues of piano playing, and superior tone and action response proving their lasting lifetime investment.
The longer the grand piano is in length, the larger the soundboard, longer the bass speaking string length, the better the piano will sound - all construction factors equal.
Very small grands under 5' are severely limited in soundboard size and string length as was the spinet piano. Many times you can get better performance from a high quality studio sized vertical piano than from a very small grand.
A good rule of thumb is to stick with a studio vertical piano unless you are buying a grand piano with a length of 5'8" or longer.
Digital Pianos -
I must get asked a hundred times a week if a digital piano is a good piano to invest in. The answer can be complicated. As a direct replacement for an acoustic piano, in my opinion, the digital piano has still not matched the majesty of a real acoustic piano. But, technology is changing practically daily and who knows what will be introduced into the market place in the future.
I can say that there is a definite place for the digital piano. If you need privacy you can practice on headphones silently. You can usually attach, if the instrument does not already have, a digital recorder for recording your playing and playing back pre-recorded material or lessons.
Also many digital instruments play other sounds from just piano and can allow you to do arranging. They are usually very light weight, certainly more portable than an acoustic piano, and don't require constant tuning.
Currently starting at prices around and under $500 they can make a great starting piano, professional studio recording instrument, or portable piano for those on the go.
For the piano player only, make sure you have the full 88 keys of a standard piano and that the keys are "touch sensitive" (a harder attack produces a louder more robust tone) and recently added is the feature of hammer weighted keys giving the keyboard the feel of a key that is weighted by a real action.
My best advise in purchasing one of these is to seek professional help from a piano tuner/technician, teacher, or someone knowledgeable concerning the features and performance you need for your particular purpose.