Apple - BOOTCAMP drive disappeared, boot Windows from EFI Boot drive

I recently installed Windows 8.1 on my MBP (running Mavericks) using Boot Camp.

Everything worked great, but I quickly realized I hadn’t made the partition big enough. So I made a backup of my BOOTCAMP drive, used Winclone 4 to create an image of the drive to restore from, and used Disk Utility to erase the BOOTCAMP partition.

When I tried to create a new partition using Disk Utility, it wouldn’t do it; I could add a partition in the “Volume Scheme” box, I could give it a name, choose a format and size, but the “Apply” button was greyed out.

So I closed Disk Utility, opened Boot Camp Assistant, and started the Windows installation again, but stopped the process after Boot Camp Assistant (successfully) partitioned the disk. I reopened Winclone and restored Windows from the image I created earlier.

Before, my alt/option startup choices were:

[my OS X drive] [Recovery 10.9] [BOOTCAMP]

but now they are:

[my OS X drive] [Recovery 10.9] [EFI Boot],

[EFI Boot] boots into Windows and everything works fine, just as it had before.

Anyways, my question is: what happened to [BOOTCAMP] (it still shows up in Disk Utility and seems fine), what is [EFI Boot], and is this a problem I need to fix or do I not need to worry about it since everything is working fine?

From apple support :

Which application should I use to create a Windows partition and to install Windows?
Use Boot Camp Assistant (located in the Utilities folder) to create a Windows partition and to install Microsoft Windows. Boot Camp Assistant works with an Intel-based Mac that has a single hard disk partition or Fusion Drive. Boot Camp Assistant creates an additional partition for the Microsoft Windows operating system or allows you to install Microsoft Windows on another drive if you have more than one internal drive.

Boot Camp Assistant does not erase your existing Mac OS X partition or any of your OS X software when it creates a new partition for Microsoft Windows.

Important: Do not use disk utilities not created by Apple to partition the drive before using Boot Camp Assistant. Doing so may erase the entire disk.

Your EFI partition is a system partition, it contains important stuff for your mac, such as the disk utillity. Don’t mess around with.

Let’s see if I can explain it simply. EFI is the bit of software built into the computer that boots your operating system. It replaces an older standard called BIOS. Mac OS X has always used EFI on Intel systems, but Windows previously only used BIOS. Each system uses a different way of handling partitions.

Bootcamp emulates BIOS so that any version of Windows can be installed. But the latest versions of Windows can also use EFI. It’s just a bit harder to install them on a Mac without accidentally messing something up, so most people just stick with Bootcamp and use the old BIOS mode.

What happened in your case I do not know for sure. It’s possible you somehow accidentally installed Windows on an EFI partition, but that seems unlikely. More likely is that Bootcamp+Windows is actually an EFI partition that gets renamed to [BOOTCAMP] in the menu. The renaming got screwed up, so it went back to the default name “EFI Boot.”

As long as both OSes work, you’re probably fine.