It's a comment you often hear about politicians, particularly at election time.

"They're all the same. There's no difference between them."

Thanks to advice from their media advisers, politicians may often sound the same, and even look the same.

Bright tie, blue suit anyone? Well for male politicians anyway.

But at this general election at least they are not the same.

There are significant differences between the main parties.

How do we know?

Well the highly respected non-partisan Institute for Fiscal Studies has just published a report comparing the parties' plans.

This is what the IFS says:

The differences between the Conservatives on one hand, and Labour and the SNP on the other are substantial. "The Conservatives need to find much more substantial spending cuts; Labour and the SNP would reduce the deficit and debt significantly more slowly."

Institute for Fiscal Studies

I'm afraid they don't get a mention in that paragraph but the IFS concludes the Liberal Democrats are somewhere in the middle, which will no doubt please them.

What do we learn from the report?

Well first, the IFS say this:

"All four parties' plans imply further austerity over the next parliament."

You'll have noticed that the SNP, the Lib Dems and Labour have claimed their plans will end austerity.

The IFS says that the Tories have failed to explain precisely where the cuts they say they will make will fall, particularly in terms of some £10 billion reduction in welfare spending.

Labour has been "much less clear about the levels of deficit reduction they want to achieve and by when" but have give more detail of how they would do it.

The Liberal Democrats, between Labour and the Tories, have "relied heavily on unspecified measures" like clamping down on tax avoidance.

Meanwhile the SNP plans do not get as much criticism for lack of detail, but the IFS implies the reduction in borrowing under them would be slower.

However, on the SNP the IFS does conclude:

They would cut less to start with but the implication of the plans they have spelled out in their manifesto is that the period of austerity would be longer than under the other three parties we consider."

Institute for Fiscal Studies
Party leader and First Minister Nicola Sturgeon has said many times the SNP's plans will end austerity. Credit: PA

It was this point which was pounced on by the SNP's opponents today.

Party leader and First Minister Nicola Sturgeon has said many times the SNP's plans will end austerity.

Labour's Margaret Curran said:

This revelation from the IFS exposes the true reality of the SNP's plans. The independent experts at the IFS show clearly that the SNP will cut Scotland's budget.

Margaret Curran, Labour Party

SNP finance secretary John Swinney called the Labour claims "ludicrous" and said the IFS study was "deeply flawed".He said:

Our plans would see borrowing not at 1.4% like Labour but at 1.6% that makes the IFS analysis of our plans deeply flawed.

John Swinney, Scottish Finance Secretary

Scottish Conservative deputy leader Jackson Carlaw said:

“This exposes the lie that the SNP would somehow usher this glorious era of wealth and prosperity.

Jackson Carlaw, Scottish Conservative Deputy Leader

Scottish Liberal Democrat leader said:

The SNP said they would bring an end to austerity. "This independent analysis shows it would be dragged out for longer, saddling the next generation with more debt. “The SNP’s reckless borrowing plans would mean the SNP will spend more on debt interest and less on public services than the Liberal Democrats."

Willie Rennie, Scottish Liberal Democrat Leader

Who is right on all of this is, of course, for the voters to decide in just over two weeks time.

However, if you have the time, there is more, a lot, lot more detail, in the full IFS report, which you can read here.