What is the difference between reserve and allowance?

Perhaps 50 years ago, accountants in the U.S. used Reserve for Bad Debts as the title of the contra account associated with Accounts Receivable or Loans Receivable. They also used Reserve for Depreciation as the title of the contra account associated with plant assets. The use of the word reserve led some readers of the financial statements to conclude that money was set aside for replacing plant assets or the uncollectible accounts or loans. To avoid this misunderstanding, the accounting profession recommended that the word reserve have a very limited use. Accountants now use Allowance for Doubtful Accounts or Allowance for Bad Debts instead of Reserve for Bad Debts. In the case of plant assets, Accumulated Depreciation is used in place of Reserve for Depreciation.