SharePoint vs the Rest
-> SharePoint vs Sitecore
SharePoint vs Sitecore
Sitecore is an enterprise cms known for it's digital maketing features and sharePoint has a publishing feature that offers cms type capabilities for internet, extranet and intranet sites. Sitecore is available through a paid license and is on the more expensive side of cms'. The publishing feature in SharePoint is included in the enterprise server version which is now the only version of SharePoint available. You can still host sites using the SharePoint publishing feature but the ability of hosting a public facing site is no longer available through Office 365, SharePoint online.
Developed as a cms and includes a digital maketing module that provides features such as campaigns and goal tracking, personalization, A/B testing and multi-variate rendering. Also provides modules for developing forms without coding as well as federated experience manager that enables the tracking and personalization of users in external sites. The platform scales well for really large sites and now owns what used to be Microsoft's Commerce Server for e-commerce sites.
Architectually Sitecore is a complex system for developers to learn and training and certification is expensive. Many times not enough planning is done around the marketing module and organizations just end up not using it and end up with only a pretty expensive cms.
Many sites have been developed using SharePoint so it's a tried and true cms. It's a feature of SharePoint so there's no extra cost. Many other SharePoint features are available for sites hosted through the publishing feature such as enterprise level search and security, web parts and services such as the term store, business connectivity and office integration.
Even though the publishing feature is included in SharePoint that doesn't mean it's free. Since SharePoint wasn't developed as a cms the entire platform must be deployed and maintained just to be able to use the publishing feature and over time this can get expensive, if you're only using SharePoint to host a site.
Both Sitecore and SharePoint are .Net based platforms but architectually they are very different. Sitecore uses a web of pipelines to process incoming requests and will route it to either a file or a controller. In this way a Sitecore site can be composed of web forms or mvc components. SharePoint is strictly an asp.net web forms platform.