In the newly released StoreFront Planning Guide (which you can find here) comes this great overview of differences between Web Interface and StoreFront.
Where StoreFront will go beyond Web Interface in the future
| Feature | Storefront | Web Interface |
| XenDesktop Deployment Scenarios | ||
| Cross farm aggregation and de-duplication | Next version | XA farm migration Only |
| Configuration through Citrix AppStudio | Next version | No |
| IPV6 support | Next version | No |
| Windows Server 2012 support | Next version | No |
| HTML 5 access on more devices | Next version | |
| Authentication Services | ||
| Smartcard support from most Receivers (LAN and AG) | Next version | Windows PNA on LAN Only |
| Unified EPA/Smart Access across Receivers | Next version | No |
| SDK for partner extensions (most Receivers) | Next version | Ad-hoc integrations, Web Only |
Where StoreFront matches Web Interface
| Feature | Storefront | Web Interface |
| Desktop Experience | ||
| Desktop restart | Yes (Receiver for Web) | Yes |
| Desktop auto launch | Yes (Receiver for Web) | Yes |
| Desktop Groups | Yes | Yes |
| Authentication & Access | ||
| Domain Pass-through and Explicit Logon | Yes | Yes |
| AG Pass-through | Yes | Yes |
| Expired Password Change | Yes | Yes |
| SmartAccess for Receiver for Web | Yes | Yes |
| Deployment Scenarios | ||
| Receiver Install & Update from Receiver for Web | Yes | Yes |
| Scalability | Yes | Yes |
| Single Site Resiliency | Yes | Yes |
| Customization | ||
| Customization (branding) | Yes (Receiver for Web) | Yes |
| Custom Language Translations | Yes | Yes |