Beware that Rowcount is deprecated as of 2012 and TOP is the keyword suggested by BOL.
We will try to see the differences between the 2 keywords:

SET ROWCOUNT
Limits the number of records to the specified number

[cc lang=”sql”]
SET ROWCOUNT 10
select * from master..spt_values
–or
select top 10 * from master..spt_values
[/cc]

How to reset the this setting
SET ROWCOUNT 0

TOP Distinctive Features

• TOP Can be specified with percentage
• Can handle tied rows using WITH TIES option flag

[cc lang=”sql”]
declare @rc int
set @rc=10
select top(@rc) * from master..spt_values

or

declare @rc int
set @rc=10
set rowcount @rc
select top(@rc) * from master..spt_values
set rowcount 0
[/cc]

Disclaimer: MS suggests to avoid using ROWCOUNT in conjunction with delete, insert and update statements