Combining Datasets with Different Features
You can use R to do that. 

The smartbind function is the perfect way to combine datsets in the way you are asking for:

library(gtools)

d1&lt;-as.data.frame(rbind(c(1,7,3),c(4,8,4))))
names(d1)&lt;-c("featureA","featureB","featureC")

d2&lt;-as.data.frame(rbind(c(3,4,5,6),c(9,8,4,6)))
names(d2)&lt;-c("featureA","featureC","featureD","featureE")

d3&lt;-smartbind(d1,d2)