PENSACOLA, FLA. -- Vladimir Posner turned up in Pensacola the other day as featured luncheon speaker on the iceberg lettuce circuit. His bottled remarks poured forth as smoothly as the store-bought French dressing that came with the salad, and they had about the same authenticity. A few observations.

Posner, 53, is identified by his lecture agent as the Soviet Union's foremost journalist. Born in Paris, where his father represented Loew's International, he came to the United States as a boy of 6. He spent his teen-age years in East Germany, then settled in Moscow. In 1970 he became commentator for the Soviets' State Committee for TV and Radio. Last year he was promoted to the rank of ''political observer'' for Radio Moscow. Posner bears an amazing resemblance to actor Richard Burton. He speaks five languages fluently. He is as slick as a wet pane of glass.

Posner came to Pensacola (for a $2,500 fee) to speak to the third annual journalism conference of the University of West Florida. His assignment was to present a Soviet view of the American press. He began by acknowledging ''profound differences'' in the two nations. Then his intellectual gears shifted to automatic transmission.

There is no such thing as a ''free press'' in either nation, he remarked. All media are controlled, his and ours. In the United States, editors exercise control over the stories that will be published and the stories that will be killed. In the Soviet Union it is a little different, but in the end it is all the same. Controls are controls.

This was a bit much for his audience of southern editors and reporters. One skeptical fellow recalled Dr. Johnson's line about the fellow who saw no distinction between vice and virtue. If he really believes that, said Dr. Johnson, ''why, sir, when he leaves our houses let us count the spoons.''

In the Soviet Union, said Posner, the role of the press is not only to inform but also to educate. Unlike American newspapers, they are not much interested in local crimes of murder or rape. When such crimes are reported, the emphasis is on determining the social forces that led to criminal behavior.

The media in both countries, he said, are alike in this respect: they hew to the government's line. President Reagan is anticommunist. The press is therefore anticommunist also.

What about dissenting opinion in the Soviet Union? The visitor was full of assurances. Under the new policy of ''glasnost,'' critical voices in fact are being raised. Great changes are coming about. Look: He was free to characterize the Berlin Wall as ''a horror.'' He had no hesitation in saying that his government blundered in reporting the nuclear reactor disaster at Chernobyl. His government also had acted poorly in the matter of the Korean passenger airliner.

All in all, it was an impressive performance by the ''foremost journalist'' of the Soviet Union. He made some criticisms that undeniably are valid in part, for example, that some American newspapers, magazines and wire services send reporters to Moscow who speak no Russian and remain for only short periods. In pleading for better people-to-people understanding, in contrast to government-to-government exchanges, he was on sound ground.

Yet Vladimir Posner never gave his audience any hint of the fundamental differences between journalism there and journalism here. To speak of a ''Soviet journalist'' is to make use of the literary device known as an oxymoron. The words contradict themselves. Posner is not a ''journalist'' in any sense known to American reporters and editors. Posner is an agent of the Soviet state, as surely as if he were attached to the Soviet Embassy in Washington. He is a propagandist. In fulfilling that role, he lectures to American universities and civic clubs. He charms the Phil Donahue show. He is an ambassador in fact, if not in law, and if much of what he peddles is baloney, it is prime baloney.

Here in the United States we sometimes get slightly obsessed with hearing ''the other side.'' The Soviet Union has no such fixation. As a spokesman for his government, Posner does a first-rate job. In listening to him, however, we may take passing note of his birthday in 1934. It fell on April 1. It figures.