As Bilbo said, they are completely different animals.
Electro-acoustic is essentially a regular acoustic guitar, generally with a piezo-electric pickup mounted under the bridge. It may be slightly shallower than a regular acoustic & often has a cutaway for easier access to higher frets. The reduced body volume will result in a quieter guitar. The pickup is connected to a small battery powered pre-amp, & can then connect to an amp via a regular 1/4" jack. This may not be enough for Rocksmith to "see" but I have no experience. So if Rocksmith is a likely option, make sure what specs are required.
/proxy.php?image=https://www.wembleymusiccentre.com/media/catalog/product/cache/1/image/650x/040ec09b1e35df139433887a97daa66f/f/a/fadb79d1-b6c0-4792-b118-9ee30142968c_425x299_2-yamaha-apx700ii-electro-acoustic-guitar-sand-burst.jpg&hash=7f6e6c51889b021dc016d3c19ef200d0
A semi-acoustic is as I described previously. A much shallower body that will make some sound unamplified but not much. It has regular magnetic pickups same as you see on a solid body electric so should be OK for Rocksmith.
/proxy.php?image=http://www.themusiczoo.com/images/3-30-11/Gibson_ES-335_Block_Antique_Red_10701713_1.jpg&hash=29508ead7aa227d3637abaa5780bd26d
seems i had my ideas of what they were the wrong way round!.....a lot of 'semi acoustic' ones advertised on the net look like the 'elctro acoustc' pictured above.....during my looking about online everywhere I've looked anyway....proper guitar stores and amazon and the like all the 'semi acoustic' named ones are actually electro acoustic then !?
don't want to hi jack this thread too much but it looks like theres plenty of confusion to had for beginners
cheers
Feel free to keep asking questions,the more information out there for beginners the better
Maybe an idea for a "beginners guide" sticky for various instruments
Just to add, for detail, to what Croc posted above, the Semi-Acoustic (Red one) has an appearance of being hollow but isn't, it has a solid block of wood running down the middle.
Glad to contribute to a "beginners guide".
just jumping back to potentially using an acoustic guitar with a lead for the likes of rocksmith etc
...I came across a youtube video of a guy using his acoustic with a separate electric pick up
Black Guitar Pickup Acoustic / Electric Transducer Clip On: Amazon.co.uk: Musical Instruments
personally i'm now edging towards a fender cd60 acoustic....having watched a lot of youtube reviews it looks a nice guitar for the money
Just be aware you can't use that Pick Up with RS directly as RS cable has a Male 1/4" Jack and goes into the Input Jack on a guitar, you could plug it into an amp (Acoustic and not an Electric one would be prefered as when you just want to play it on its own it will sound a lot better) and if the Amp has an output socket you could plug the RS Jack into that but not sure how that would affect any lag.
The CD60 is a great guitar for the money, have you tried one yet?
6.35mm Audio Coupler - MONO
Like I said, you can't use that Pick Up directly with RS, apart from other possible issues.
just a quick search on amazon bought that one up...the guy on youtube was using something similar with the right size jack I'm guessing....just he had to use a female coupler in order to connect 2 male jacks together....the pick up lead and the xbox lead.....well his example was the playstation but same thing I guess.
ref the cd60.....not been able to look at one in the flesh but watched loads of youtube clips and reviews last night....looks great for the money...meant to be quality finish and parts,'easy' to play...holds it tune well etc etc.
looks pretty cool in black....seen the guitar on its own for 100 quid and a starter pack....with a tuner...strings,strap.picks and dvd for 114 quid....seems pretty good value
...plus its a fender
Just making you or anyone else aware of any issues that may arise,never said it wouldn't work but RS is designed for Electric Guitars, the chord structures are for Electric Guitars (But can still be played on Acoustic) and when you try and play down the fretboard it is harder without a cutaway on an Acoustic and it will make it more frustrating than necessary as learning guitar can be a frustrating learning experience as it is and making it harder for yourself won't help.
Also as there is no Pre-Amp in an Acoustic (Pick Up) you will need to hit the strings harder for the sound to register with RS, something else which may hinder the experience as you'll be hearing the sound through the TV and the Acoustic which can be off putting.
Being a Fender doesn't mean it's a good guitar, (The CD-60 is good value and does sound good though) there are plenty of 'named' guitars out there that are not very good, please don't get caught up in the hype, that's why it is important that you try a guitar for yourself.