User control Vs. Custom control

Factors	User control	Custom control
Deployment	Designed for single-application scenarios Deployed in the source form (.ascx) along with the source code of the application If the same control needs to be used in more than one application, it introduces redundancy and maintenance problems	Designed so that it can be used by more than one application Deployed either in the application's Bin directory or in the global assembly cache Distributed easily and without problems associated with redundancy and maintenance
Creation	Creation is similar to the way Web Forms pages are created; well-suited for rapid application development (RAD)	Writing involves lots of code because there is no designer support
Content	A much better choice when you need static content within a fixed layout, for example, when you make headers and footers	More suited for when an application requires dynamic content to be displayed; can be reused across an application, for example, for a data bound table control with dynamic rows
Design	Writing doesn't require much application designing because they are authored at design time and mostly contain static data	Writing from scratch requires a good understanding of the control's life cycle and the order in which events execute, which is normally taken care of in user controls