I would say that, and from the perspective of the consumer, they are totally different. The consumer is completely unaware od the subliminal advertising. The cognitive side is absent from his purchasing decisions.

At an operative level, consumers are unaware of subliminal advertising while they can become aware in the case of surrogate advertising. Surrogate advertising relies on strong consumer associations between 2 or more brands while subliminal advertising simply relies on brand prominence

Subliminal advertising is related to consumers' subconscious. Normally when we sense anything, we are doing it consciously. We pay attention to a particular object, we sense it (see, touch, smell) and thus our brain processes it. But all that requires a lot of processing from our brain as we make conscious judgements and opinions about it. Unfortunately, there is just too much data/input at any given instance for us to process all at once so our conscious mind sifts the good data (the one we actually want to pay attention to) from the bad data (the unimportant one). For example when I go into a class to teach my students, I'm paying attention to my lecture and my students' academic needs. Thats all good data. But many of my students are holding notebooks or water bottles or some other stuff that has something written on it. (small or large). That's the bad data, the one my brain doesn't want to process. BUT just because my conscious part of the brain didn't process it, doesn't mean that the bad data did not get inside of my brain. Almost everything that is within one's peripheral vision is stored into the brain. However it is not part of our conscious mind. This means we can't retrieve it consciously. However it does effect our judgements and evaluations of related objects.

A very famous example that people quote is that of an american cinema where during a movie, out of millions of frames, one of the frames showed a brand (rumored to be Coca Cola) and after the movie ended, the sales of coke spiked for the cinema which was not usual.  

Surrogate Advertising, on the other hand, is somewhat unethical form of advertising. It is done for those products that cannot be advertised on TV. For example, in India, promotion of alcohol is not allowed. So what they do is that they create a separate (but somewhat related) product like soda and promote soda on television with the same brand name. This gives that top of the mind brand recall. A good example is Bacardi Blast Music CD for Bacardi Spirits/Alcohol. 

I hope it helped.

Dear Mukul,

Indeed there are important differences ranging from the idea or design to implementation.

In subliminal advertising it is almost mandatory to take actions focus group, to check the effectiveness of the idea or design, especially for the effects are aligned with desired. In many cases, these focus groups, allow to find ideas that will help you achieve the goals.

Another highlight has to do with the effects of subliminal advertising are short temporal scope, ie they are for the short and very short term.

I hope I've helped; many lucky, best regards,

Federico