There is a big difference between attorneys who specialize in transactional and lawyers who specialize in litigation. It's the type of legal problem they are most likely to encounter. Transactional lawyers deal primarily with contracts, real estate transactions, business formation, intellectual property issues, etc. Litigation attorneys deal with disputes involving corporations. Partnerships, trusts, estates. Insurance claims. Personal injury cases.
Both types of attorney require different knowledge and skills for each case. For example, if you were considering hiring a transactional attorney, he would probably need to know how to draft agreements, prepare documents, negotiate terms, handle conflicts, etc. A litigation attorney needs to be familiarized with the rules for evidence, statutes, limitations, rules on discovery, etc.
There may also be differences depending on the location of the client. A New York City attorney might not have the same knowledge as an attorney practicing in California. An attorney in Florida would not know as much about Texas laws as one who is practicing in Texas.