In countless aspects, Apple Computer Inc. is vastly different than longtime rival Microsoft Corp. But recently Apple has been accused of similarly ostracizing software developers who would rather not go head-to-head with Apple’s growing stock of applications.

Intentionally or not, “Apple is pursuing a strategy that locks out their third-party software vendors,” said Avi Greengart, an analyst with Jupiter Research.

In the latest instance of an outside developer abandoning the Macintosh platform, Adobe Systems Inc. announced in July that the latest overhaul of its flagship video editing program Premiere no longer would work on Macintosh computers. Adobe said the software version will only be compatible with Microsoft’s Windows XP operating system (OS).

Adobe’s new Encore DVD-creation program will not have a Macintosh version either. Both programs will be part of a Windows-only software package called Adobe Video Collection.

Apple and Adobe have long shared a customer base of “creative professionals”–Adobe’s release last year of Photoshop for the Mac OS X operating system, for instance, helped boost sales for both companies. But Apple has been introducing more and more of its own software in recent years, and some of it competes with Adobe’s.

“If Apple does it, there’s no room for a third-party developer,” said David Trescot, senior director of Adobe’s digital video group. “Why do it when the [OS] provider could give it away for free?”

In the video editing arena, Apple offers Final Cut Express and Final Cut Pro. Also, in the past three years, it has introduced consumer-friendly digital media applications such as iMovie and iDVD and included them for free on most Apple computers.

Analysts say companies that offer the OS, the hardware, and the software have the advantage of making their products work seamlessly together and bundling them so they are free or cheaper than if sold alone.

Outside software vendors have voiced similar complaints about Microsoft in the past, saying Microsoft’s access to its underlying code gave it an inside track on making its own add-on products run more smoothly than others.

With Apple, Microsoft has found itself on the receiving end. Earlier this year, Microsoft said it would stop making its Internet Explorer web browser for Macs, citing Apple’s recent introduction of its own Safari browser. Safari already has gained attention for its speed and features.

“Apple has access to functionality in the OS that Microsoft doesn’t,” Jessica Sommers, product manager for the software company’s Macintosh Business Unit, said at the time. “They can do things because they’re developing on their own OS that we as a third-party programmer can’t do.”

Phil Schiller, Apple’s vice president of worldwide product marketing, said Apple branches out with products when it thinks there is a competitive hole. “When we find a need, and we have the ability to fill it, and it fits into what we’re doing, we’ll do it,” he said.

There are third-party software products, however, that Apple considers “very important” to its customers, he said, citing the Macintosh versions of Microsoft Office and Adobe Photoshop.

Adobe’f’s defection did not surprise analysts. Making a piece of software compatible with multiple platforms takes time, effort–and money. Add to that the slow economy and Apple’s overall desktop market share of only 5 percent, and companies are less willing to make the investment of building for the Mac OS if they expect a low profit return, said Paul Ritter, an analyst with industry research firm Yankee Group.