Answer:
A low-level programming language is called that because it is closely tied to the machine architecture. As a result, it isn't very portable. A program written for an Intel chip will not run on a Sparc-chip because the instruction set is very different.
Low level programming languages require great amounts of detail in the design and implementation, and generally cannot be viewed easily in terms of their overall structure because they are done at a low level.
In contrast, high level programming languages may be close to English-like, and can be translated or compiled to any hardware platform usually without regard for the actual machine architecture.