A lawyer who specializes exclusively in transactional legal is different from one who specializes only in litigation. This is because they will encounter different types of legal problems. Transactional lawyers are primarily concerned with contracts, commercial transactions, corporate formations, intellectual properties, and the like. Litigation attorneys specialize in disputes involving corporations or partnerships, trusts and estates as well as insurance claims and personal injury cases.
Each type of case requires different skills and knowledge. 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 lawyer must be familiarized with the rules regarding evidence, discovery and statutes of limitations.
You might also find other differences depending on where your client is located. A New York City attorney might not have the same knowledge as an attorney practicing in California. A Florida attorney might not be as familiar with Texas laws as someone who practices in Texas.