Your goal in private practice is to take care of the individual needs of each patient that you see in a way that works for the client (your main customer). You do whatever it takes to take the best care of each individual patient to the extent that the client allows. So you generally take care of a greater range of things. You need to know the current trends in pet products, available diagnostics, drugs, etc... You deal with referral situations with pets that need specialty care, and do whatever it takes to keep each pet alive with a good quality of life for as long as possible. You deal with needing to answer all the questions that people have about their pets (from what to feed them, why does my pet do that? How do I stop my pet from... etc...). You have to work within the confines of how the client wants to manage the pet at home. Your ability to care for the pet really depends greatly in the client. The cost of every little thing you do matters. The pace of your job in this setting is dependent on how busy the practice is. It can be incredibly fast paced, because you don't want to keep your appointments waiting.
Your goal as a shelter vet is population health, and individual needs of each patient is secondary. You have individual patients that need more care, the pets with the wretched mouth that needs full mouth extractions, trauma patients that need some basic ortho procedures, eyes that need to be taken out, the occasional medicine cases. How many of these more extended care cases you have the opportunity to handle depends greatly on the available resources of the shelter (your main customer) in terms of time/money available. Your focus is not as much on individualizing care to meet the needs of each animal, but rather to come up with as all encompassing and streamlined, dummyproofed protocol as possible so that laystaff can do a majority of the care instead of you. Vaccination, deworming, cleaning, testing, isolation, anesthesia protocols. All that is very important. You have a huge role in preventing and dealing with disease outbreaks. You also deal with a lot of cruelty and hoarding situations. Those are dealt with a little differently from the rest of your shelter cases because they are legal cases and the animals are evidence. You don't need to know about all the newest products out there, because a vast majority of it you have no need for. In some shelters you have decision making power, in others, all your decisions go through laystaff management. You generally don't need to ask for permission to do every little thing for every patient. And to an extent, as long as you work within your budget, you can decide on treatment for the animals without getting others involved (e.g. Puppy with a broken leg). For some shelters you have one vet who does everything, others separate the job in those that primarily do spay/neuter vs those that primarily take care of medicine. For a spay/neuter vet, your job is to be as efficient as possible and fix as many animals as you possibly can. Your goal is to make sure everyone leaves the building altered.
Physical danger really depends on how well the place is managed. I've probably had to put myself in more physical danger in private practice than in shelters. I ran into more dangerous animals in shelters, but the places I was at were better equipped than most private practices in dealing with them. We had dart guns, used rabies poles more often, syringe poles, etc... The fractious animals got euthanized, and didn't need xrays and blood draws and nail trims...
In both settings, your autonomy and ability to practice the way you want depends entirely on how each place is managed. There are horrible shelters with horrible management that I would never work for because as a vet your hands are tied all the time by ignorant laystaff who have no idea what they're talking about. There are horrible private practices with absolutely nightmarish ways of operating and treating their vets. Just like there are practices with clientele that can't afford most of what you want to offer, there are many shelters that can't afford to let you treat many of their pets so that essentially all non healthy super adoptable pets (and even some of those) get euthanized. Some very well funded shelters can do a ton of stuff for each patient.
