Hewlett-Packard's $25 billion mega-deal to buy Compaq Computer gives the European Commission a say for the second time in a year on an all-American deal - but this time with a big difference.

Earlier this year, European Competition Commissioner Mario Monti rejected General Electric Co's proposed purchase of Honeywell International Inc after American competition authorities had cleared it.

That decision exposed differences between American and European antitrust authorities, but experts said this deal was fundamentally different.

The GE case involved aeroplane engines made by GE, avionics made by Honeywell - and GE's ability to use its financing arm as a sales tool for both products.

The lawyer noted that Compaq and HP have overlaps in the areas of low-end servers and personal computers, but said those areas are highly competitive. The market is so volatile that the lawyer said the Commission may not be concerned.

Large American companies that do a lot of business in Europe must win official approval that they do not compromise their competition, as must European companies in the US.