Truthkeeper88. Grimm's Kinder-und Hausmarchen, erster theil (1812) (2012) [online image] Available from: http://commons.wikimedia.org/wiki/File:Grimm%27s_Kinder-_und_Hausm%C3%A4rchen,_Erster_Theil_(1812).cover.jpg [Acessed 30th March 2015]
There was nothing particularly wrong with the first edition of the tales but they are a lot more blunt and unpretentious and they had not yet been censored with the more sentimental Christianity and puritanical ideology of the later volumes. Conversely, the brothers originally kept their hands off the tales more and reproduced them very similarly to how they had originally heard them. This is because the tales in the book are not originally their own, they retained others voices from the storytelling of various friends and anonymous print material. They were then edited by the Grimms, who wanted to retain their ancient and contemporary voices as much as possible. However as editions went on they became more and more edited and more and more the Grimm's brothers own tales. It is in the original two volumes that the tales are the most vivid as here they made the greatest effort to respect the voices of the original storytellers or collectors and before they'd began to heavily edit them to appeal more the the middle-class reading audiences.
The brothers began collecting the stories from all around in 1808, compiling tales, myths, legends and pagan beliefs. In 1809 they sent about 54 tales to a friend, copying a version for themselves. The friend never made use of the tales and left them in a monastery, which was fortunate as the Grimms destroyed the texts after using them for their first edition of their book. The manuscript they sent to the friend was only discovered in 1920 and has provided researchers with important information about the Grimm's editing process. During the editing process things were cut out such as overt cruelty, eliminating tales which might be offensive to middle-class taste, replaced tales with more interesting variants, added some Christian homilies, and stylized them to evoke their folk poetry and original virtues.
phrood - commonwki. Grimm. (2005) [Online Image] Available from: http://commons.wikimedia.org/wiki/File:Grimm.jpg [Accessed 30th March 2015]
Some of the changes which are more obvious between the editions are in 'Little Snow White' and 'Hansel and Gretel' where the wicked stepmother is actually a biological mother and these characters are changed to becomes stepmothers in 1819 because the Grimms thought motherhood was sacred. The first edition of 'Rapunzel' is a very short tale where Rapunzel falls pregnant, however the 1819 version is a lot longer, more sentimental and has no pregnancy in it.
These 50 years of drastic alterations added on to the obvious issue of the tales being told to the brothers not only in German but it Italian, French and English then over the years being translated into over 40 languages, including the English version used for this project means that anyone you speak to may know a slightly different version of the same fairytale, adding layers of interest and mystery to the stories.