When referring to an individual cell, we’re usually referring to the value within that cell. So a user might ask “what value is in the FirstName field?” when referring to an individual record.
When referring to the whole column, we’re usually referring to the name of the column, its data type, constraints, and any data contained within that column.
Using this definition, a developer might ask another developer “what data type are you using for the FirstName field?”. This could just as easily have been “what data type are you using for the FirstName column?”.
So the actual usage can depend on the context.
However, some experts argue that fields and columns are two different things:
Columns are not fields. Fields get meaning from the application reading them — and may have several meanings depending on the apps. Fields are sequential within a record and do not have data types, constraints or defaults.
In any case, as mentioned, the terms field and column are often used interchangeably, which is probably fine in most cases – where no distinction needs to be made.
Also, the ANSI/ISO Standard for SQL defines a field as part of a temporal value (eg, year, month, day, hour, minute, second). So this is yet another thing to consider when trying to decipher what someone means when they say “field”!