Once upon a time, the cathode ray tube was the only display screen technology in common use. Televisions, arcade consoles and computer monitors all used this one bulky technology. Usually, the screen surface was curved, but sometimes these bulky lightbulb-like tubes did have a flat screen.
Today, there are a number of technologies in use -- light-emitting diodes and liquid crystal displays among them. These technologies allow the construction of panel displays, much thinner and lighter than the old-fashioned glass tubes.
The main difference is that the old tech was a tube display, the newer techs are panel displays. The simplest way to make this distinction clear is to call the old tech a "CRT TV", any of the new techs a "panel TV". The same distinction works for other displays as well, such as "my computer still has a CRT monitor, and I'd like to upgrade to a wide-screen panel."
The reason I don't recommend calling all CRT TVs "tube TVs" is that the earliest CRT units had many other vacuum tubes in their construction. Later CRT units were built using transistors, leaving the CRT itself as the only necessary tube. The phrase "tube TV" suggests a pre-transistor television rather than a merely non-panel television.