I know the integer format would be different between big-endian machine and little-endian machine, is it the same for float point format (IEEE 754)?
The IEEE754 specification for floating point numbers simply doesn't cover the endianness problem. Floating point numbers therefore may use different representations on different machines and, in theory, it's even possible that for two processors integer endianness is the same and floating point is different or vice-versa.
See this wikipedia article for more information.