After struggling in the first four races of the year, McLaren will trial the first phase of a major series of upgrades in free practice at Barcelona, with further packages scheduled for introduction in the following races.
The 2009 world champion said that the changes will be obvious to the naked eye, although does not expect the new parts to transform the McLaren into a race-winning machine yet.
"There is a lot that is different, you will be able to see [the changes to] the aerodynamics of the car and you will understand the difference in airflow of the car," said Button.
"It is still the same colour, but the edges have changed.
"There are some really cool-looking little bits on the car but I don't think it is going to be enough to fight right at the front.
"We will see an improvement and hopefully that will help us understand the airflow of the car a little bit better."
Button stressed that the key for the team is to ensure that the new parts perform as expected, showing that McLaren has got on top of the windtunnel-to-track correlation problems that have contributed to its 2013 struggles.
But he does expect the car to be quicker at the Spanish GP, admitting that a satisfactory step would be for the McLaren to be able to make it to Q3 comfortably.
"We should be happy with that," he said when asked by AUTOSPORT whether just getting into the top 10 easily would suffice.
"We have got into Q3 in every qualifying session but we were helped a lot in Australia by it being wet.
"I have been in Q3 every race, which is a surprise but a car that can get into Q3 and not be right on the edge of falling out in Q2, that's a good step forward.
"But the more important thing is understanding the correlation with the windtunnel."
McLaren has run the upgraded car in a straightline test, with Button confirming that this did suggest correlation had improved.
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