What are the Tax implication for US company hiring offshore software
The main implication is the withholding of taxes from the payments. You must withhold and remit to the IRS 30% of the payments sent to the non-resident contractor.
How different is it from hiring a consultant from US in tax files vice
If you're asking about the difference between the resident and non-resident contractors - then that's the difference: for non-residents you're required to withhold, for residents you're not required to withhold (unless there's a specific withholding requirement for that particular person).
Is taxes hire for US Company to hire offshore consultant
Higher, you mean? No, there's no tax on hiring consultants (as contractors, that is), whether on-shore or off-shore. The withholding is from the money you pay to your consultant, its the consultant's tax, not yours.