The parks will be remarkably similar, including rides that duplicate natural disasters like earthquakes and rides that put visitors into the middle of movie scenes being ''acted'' by lifelike dummies. In addition, both include behind-the-scenes looks at how movies are made, including stunts and special effects.

Universal, which created the original movie theme park with its highly successful Universal Studios tour in California, says that Michael D. Eisner was shown the plans for its Florida park before he became chairman of Disney and that he has since borrowed some of the ideas for the Disney park.

As a result, Mr. Stein said, ''We've had to change the concepts from our original plan.''

Mr. Stein argues that in 1987 Disney announced it would build a $600 million tourist attraction near Universal in California as a way of making Universal hesitate about going ahead with its Florida park. Disney has since abandoned the California plan.

In addition, some Universal executives maintain that Disney is pressuring county tourism officials to make sure that when the travel industry brings 3,500 people to the Orlando area next year for its convention, the visitors are kept away from Universal's movie park. The officials, not wanting to get involved in the feud, declined to comment.

Disney officials dismiss Universal's charges as insulting. They say that Mr. Eisner never saw plans for the Universal park and that Disney has been considering a movie theme park since the 1950's. They also say they are so successful they have no need to pressure Florida tourism officials to slight Universal. Indeed, the Disney-MGM park has been doing so well, drawing up to 25,000 people a day at $29 a head for adults, that Disney has announced plans to double the size of the park. 'Sands of Fantasy'

''Universal's arguments are built totally on sands of fantasy,'' said Erwin Okun, Disney's senior vice president for corporate communications. ''They have been planning their park since 1981. Now we have opened ours quite successfully, and I think they are, right now, sucking on particularly sour grapes.''

Disney's strategy for its movie park's success is the same as for its whole 28,000-acre operation here: lure tourists to Disney World and then provide them with hotels, stores, restaurants and so much entertainment that they never venture out to any of Orlando's other attractions. Universal's strategy is to let Disney lure the tourists to Orlando, then inundate them with so much advertising here - billboards, for example - that their curiosity is piqued and they desert Disney for a few hours to visit Universal.