Context (New York Times):
Besides piling into Treasuries, institutional investors are also seeking out the safety of cold, hard cash, pouring billions into commercial bank accounts backed up by the Federal Deposit Insurance Corporation.
cold cash: Also, hard cash . Actual currency (bills and coins); money immediately available, paid at the time of a purchase.
The Oxford Advanced Learner's Dictionary lists cold cash as American English, and hard cash as British English.
Is the OALD correct? Is there a difference between these two terms or not?