Everyone else has covered this for the most part, but I don't mind adding one bit of information. Table variables, unlike temporary tables, do not have statistics created on them. This means that they are treated as if they have one row for any joins or searches done against them. When they only have a few rows, this doesn't matter, but when they have hundreds or thousands of rows, it makes a huge difference in the execution plans and the performance. It's just something to keep in mind.