[sql-server] Is there any difference between DECIMAL and NUMERIC in SQL Server?

Is there any difference between DECIMAL and NUMERIC data types in SQL Server?

When should I use DECIMAL and when NUMERIC?

They are exactly the same. When you use it be consistent. Use one of them in your database

To my knowledge there is no difference between NUMERIC and DECIMAL data types. They are synonymous to each other and either one can be used. DECIMAL and NUMERIC data types are numeric data types with fixed precision and scale.

Edit:

Speaking to a few collegues maybe its has something to do with DECIMAL being the ANSI SQL standard and NUMERIC being one Mircosoft prefers as its more commonly found in programming languages. ...Maybe ;)

This is what then SQL2003 standard (§6.1 Data Types) says about the two:

 <exact numeric type> ::=
    NUMERIC [ <left paren> <precision> [ <comma> <scale> ] <right paren> ]
  | DECIMAL [ <left paren> <precision> [ <comma> <scale> ] <right paren> ]
  | DEC [ <left paren> <precision> [ <comma> <scale> ] <right paren> ]
  | SMALLINT
  | INTEGER
  | INT
  | BIGINT

 ...

21) NUMERIC specifies the data type
    exact numeric, with the decimal
    precision and scale specified by the
    <precision> and <scale>.

22) DECIMAL specifies the data type
    exact numeric, with the decimal scale
    specified by the <scale> and the
    implementation-defined decimal
    precision equal to or greater than the
    value of the specified <precision>.

They are synonyms, no difference at all.Decimal and Numeric data types are numeric data types with fixed precision and scale.

-- Initialize a variable, give it a data type and an initial value

declare @myvar as decimal(18,8) or numeric(18,8)----- 9 bytes needed

-- Increse that the vaue by 1

set @myvar = 123456.7

--Retrieve that value

select @myvar as myVariable

Joakim Backman's answer is specific, but this may bring additional clarity to it.

There is a minor difference. As per SQL For Dummies, 8th Edition (2013):

The DECIMAL data type is similar to NUMERIC. ... The difference is that your implementation may specify a precision greater than what you specify — if so, the implementation uses the greater precision. If you do not specify precision or scale, the implementation uses default values, as it does with the NUMERIC type.

It seems that the difference on some implementations of SQL is in data integrity. DECIMAL allows overflow from what is defined based on some system defaults, where as NUMERIC does not.