HTTP filter and URLScan
The main difference between URLScan and the HTTP filter is that URLScan applied to all HTTP traffic, whereas the HTTP filter can be configured on a per-rule basis. This gives you greater control over your HTTP policy.
Another difference is that the HTTP filter does not include this functionality from the URLScan tool:
Logging is incorporated as a separate field (FilterAction) in ISA Server logging.
RejectResponseURL is a mechanism used by URLScan to redirect the requesting client to a different page. ISA Server includes error response pages.
UseFastPathReject was an option to simply drop the request, rather than using the RejectResponseURL
DenyUrlSequences is replaced by the Signatures tab of the HTTP filter properties.