The difference is choice.
In the Apple model, yes, they have built that walled garden. Yes, they are generally sealed units with limited upgrade options. But with Apple in 2014, they're just one vendor among many viable alternatives. Depending on who you ask, they're somewhere between 8% and 15% of the market. That leaves a huge selection of alternate vendors from which to choose.
Microsoft, lest anyone forget, is a convicted (unfortunately never punished) monopolist. Is the late '90s they had something like 98% marketshare. In MS' world, you have no choice but to submit to his will and his ecosystem. You would not be free to leave and switch vendors because there would be no alternatives available. And while Gates may have recently been able to buy them a better reputation with his so-called charity work; you're a damn fool if you think he is anything but a viciously ruthless businessman who wanted nothing less than complete dominance over you.
Hmm.. I kind of hate defending Microsoft after having spent so much effort supporting the MS boycott. However, locking you into hardware vendors was never a MS thing. MS generally did their evil by forcing companies to sell MS and no alternative OS based products. They also did their thing buy stealing competing software outright. In the 90's there were thousands of examples on the now defunct vcnet.com (the url was vcnet.com/bms but no more) boycott site where the evil was being documented.
Bash MS, yes. But do it for valid reasons or you just shoot holes in your cause.