Consumers, beware.

That's the word from a number of banking experts following reports that somethrift institutions, commercial-lending companies, and banks are offering savings certificates - called "subordinated capital notes" - that have attractive high yields over long periods of time. Outwardly, the certificates very much resemble conventional certificates of deposit (CDs). The problem is that they are notCDs.Banking experts say the distinction is far from inconsequential. Certificates of deposit are relatively high-yield savings instruments sold by financial institutions for a set term - say one to three or five years. If sold by a bank or savings-and-loan association, they are federally insured, by the Federal Deposit Insurance Corporation (FDIC) in the case of banks, or the Federal Savings and Loan Insurance Company for thrifts.

By contrast, the new savings instruments being sold by some financial institutions around the United States (primarily in Florida, New York and the mid-Atlantic region, and the Upper Midwest) are not federally insured.

Designated as capital notes (and not bonds, which have important legal claims against the assets of a financial institution), they offer high interest rates, usually at 12 percent or more. And the terms can stretch from one to 15 years. Some one-year subordinated notes are being offered with yields above 10 percent, which equals or beats most current money-market rates. Advanta Corporation, for example, a Pennsylvania-based finance company, offers a one-year subordinated instrument with a yield of 10 percent. In some communities, subordinated notes are being directed toward older persons, particularly retirees.

Conventional CDs are available in the same range. Citytrust, based in Connecticut, offers a six-month CD with a minimum deposit of $25,000, yielding 10.47 percent, based on 10 percent annual interest rate.