From what I've seen Democrats seem to look at the data and studies on the situation to figure out what works best for the economy and the people. Republicans tend to vote on ideology regardless of who it benefits (turns out it mostly benefits those who sponsor their compaigns, surprise surprise).

As for "voting in lock-step", nope not even close. Good analysis of many major votes here: https://www.reddit.com/r/cantmisslists/comments/7gaq5z/both_... Democrats vote to keep the government transparent, honest and benefiting the people way more than Republicans.