The two are indeed different.
See https://www.irs.gov/businesses/small-businesses-self-employed/tangible-property-final-regulations#Ad...
A de minimis safe harbor election
Note: Effective for taxable years beginning on or after January 1, 2016, the Internal Revenue Service in Notice 2015-82PDF increased the de minimis safe harbor threshold from $500 to $2500 per invoice or item for taxpayers without applicable financial statements. In addition, the IRS will provide audit protection to eligible businesses by not challenging the use of the $2,500 threshold for tax years ending before January 1, 2016 if the taxpayer otherwise satisfies the requirements of Treasury Regulation § 1.263(a)-1(f)(1)(ii).
See https://www.irs.gov/businesses/small-businesses-self-employed/tangible-property-final-regulations#Si...
There is also the safe harbor for small taxpayers for improvements in Treas. Reg.§1.263(a)-3(h):
See https://www.law.cornell.edu/cfr/text/26/1.263(a)-3
