The biggest differences are in how these three characters are handled.
Embedded double quotes in fields.
An escape character is sometimes used to introduce a double
quote, or in place of it.
Embedded line-feeds in fields.
This one is also escaped sometimes. Often like in C ("\n")
Embedded commas in fields.
Again, an escape character is sometimes used in place of the comma
Excel vs. Leading Zero & Space
A particular aspect of how
Excel uses CSV has become a considerable source of
confusion and uncertanty.
always remove leading spaces
always remove leading zeros from fields before displaying
them
but depending on the system's regional settings, it may expect a semicolon as a separator instead of a comma, since in some languages the comma is used as the decimal separator
Microsoft Excel will open .csv files,
Also, many regional versions of Excel will not be able to deal with Unicode in CSV