Hi Khaled,
InfoPath Filler is a component of InfoPath. To fill out the forms using InfoPath Filler, end users should have InfoPath installed.
For InfoPath 2010, InfoPath Designer 2010 and InfoPath Filler 2010 are included. InfoPath Designer and InfoPath Filler are installed on client computers as part of Microsoft Office Professional Plus 2010. You can refer to this article to know more about InfoPath 2010:
office.microsoft.com/.../introduction-to-microsoft-infopath-2010-HA101821251.aspx
Thanks,
Young Yang