2 practical application?

Question

1)a balanced twin coaxial line
2)an unbalanced coaxial line

Answer 1

Well thats confusing since you mixed terminologies. Normally you use coaxial line to run a signal more more efficiently and the same with twin lead or any other twin wire configuration. they both would be to bring signal from one place to another assuming they existed as termed. May be these terms are from another country, I live in the USA.

Maybe you mean balanced to unbalanced converters or Baluns which are used to convert the 300 ohms of a twin lead to the 52 ohms of a coaxial line.