The Javelin is in the Curve family. They're calling it the Curve 8900.
The Bold is the successor to the 8800-series and has the same external dimensions. So it's bigger then the Javelin. Here's a comparison of the Bold to the 8300 (same dimensions as the Javelin):
GSM Arena. Don't take any other stats of the 8300 for Javelin stats, just the overall dimensions.