R help - May 2004 - Agnes and Hclust

Hi,

I want to know if there is a difference between the two
hierarchical methods Agnes and hclust when there are used with
the same method and the same metric on the same data! I ask
this question because I executed the following program: 
hc <- hclust(dist(AGRIINSTTableFinaleCR), "ward")
agnes<-agnes(dist(AGRIINSTTableFinaleCR),method="ward")
And clusters are not the same even if they are a little similar!

Is anybody know why i have this difference?

Thanks in advance

Nicolas BOUGET