Which of the following statements is true regarding veins versus lymphatic collecting vessels?
veins and lymphatic vessels have a different number of tunics.
veins have thinner walls than do lymphatic vessels.
veins tend to form more branches (anastamoses) than do lymphatic vessels.
veins have fewer internal valves than do lymphatic vessels.

The correct answer is: Veins have fewer internal valves than do lymphatic vessels.

Some of the differences between blood (veins) and lymphatic vessels  are:

•Valves of lymph vessels are more closely spaced than those of veins

•Blood vessels are not interrupted (closed circulatory system) while lymphatic vessels are interrupted via lymphatic nodes.

•Veins are connected with the central pump of the circulatory system-heart, while lymphatic vessels don’t have such structure.