What you are looking at are three different white things: snow on Greenland, clouds and my favorite of course, the sea ice. You may find it hard to pick out the different white features. This is because it is a true colour image.
But as the MODIS web site says:
[the] detectors measure 36 spectral bands between 0.405 and 14.385 µm, and it acquires data at three spatial resolutions -- 250m, 500m, and 1,000m.
From the image web page you can choose to look at different spectral bands. This is the image showing Bands 3, 6 and 7.
Now it is a little easier to pick out the different white features. So white is cloud, Orange is snow on Greenland and red is the sea ice. I very much like the way the sea ice is broken up into threads and streamers stretching out into the North Atlantic.
The final option for the quick imagery download is MODIS bands 7, 2 and 1.
In this final image the snow is cyan coloured, and the clouds white to cyan depending on the altitude of the clouds. And my favourite sea ice is the darker blue.
It is always worth a look at the whole Arctic MODIS imagery if you have a spare moment. If you see an area that is cloud free, click on it to download a much higher resolution image.