When we had 20+ chickens, it was often impossible to tell who was laying what. I never was sure which individual was laying the pinkies in the egg picture above (in the the new header)1.
When you only have two chickens, it's easy to tell the difference in the eggs.
On the left is an egg from the Marans hen. They're supposed to be very dark eggs, but sometimes they turn out speckled. You don't find chickens advertised as laying spotted eggs, but most of our hatchery Marans did, from time to time.
On the right is an egg from the Easter Egger. They are usually green or blue. This one is such a pale green that it didn't come through well in the photo.
Common wisdom has it that chickens lay fewer, but larger, eggs as they age. I've found that to be true for all the types we've had except the Marans. Hers continue to be smallish, but she's laying more often now than ever. All our chickens' eggs have gotten lighter in color each successive season.
1That seems to be the picture that people remember most from the blog. (Every time I look at it, it bothers me that I didn't get them lined up a little straighter.) It was from my first month of blogging, so I suppose you could say it's been all downhill from there. Click here for the larger, right-side-up original version.