The answer, in my opinion, is no - there is at least one fundamental difference when it comes to core economic issues It seems to me that traditional "liberals" in our current parlance are those who focus on using taxpayer money to help better society. A "progressive" are those who focus on using government power to make large institutions play by a set of rules.
To put it in more concrete terms - a liberal solution to some of our current problems with high energy costs would be to increase funding for programs like the Low Income Home Energy Assistance Program (LIHEAP). A more "progressive" solution would be to increase LIHEAP but also crack down on price gouging and pass laws better-regulating the oil industry's profiteering and market manipulation tactics. A liberal policy towards prescription drugs is one that would throw a lot of taxpayer cash at the pharmaceutical industry to get them to provide medicine to the poor; A progressive prescription drug policy would be one that centered around price regulations and bulk purchasing in order to force down the actual cost of medicine in America (much of which was originally developed with taxpayer R&D money).
Let's be clear - most progressives are also liberals, and liberal goals in better funding America's social safety net are noble and critical. It's the other direction that's the problem. Many of today's liberals are not fully comfortable with progressivism as defined in these terms. Many of today's Democratic politicians, for instance, are simply not comfortable taking a more confrontational posture towards large economic institutions (many of whom fund their campaigns) - institutions that regularly take a confrontational posture towards America's middle-class.
Here's the thing - we all want to see autoworkers' health care preserved, and we all want to see better fuel efficiency standards for cars. But is this really the road we want to go down as a society? I'd say no. The fact is, the auto industry should be forced to produce more fuel efficient cars through higher government fuel efficiency mandates, without taxpayers having to bail out the industry. It's not like those mandates would be asking the industry to do something that doesn't make good business sense - demand for higher fuel-efficiency cars is skyrocketing.
Paying off corporations to do what they already should be doing sets a dangerous precedent - it sends a message to Big Business that they can leverage their irresponsible behavior into government handouts. In this case, the auto industry would be leveraging its refusal to produce more fuel efficient cars and preserve its workers' health care into a giant taxpayer-funded subsidy.
Obamas health care for hybrids proposal:
Demand for more fuel efficient cars is skyrocketing: