This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
The EL ignorance declaration in web.xml would apply to complete web app where as the EL declaration in jsp just applies to that particular jsp page.
If you specify "true" in web.xml to ignore el & you specify false in all the jsps to isELIgnored then the jsp declaration would take precedence over the web.xml declaration & all the ELs in all the JSPs would be evaluated.