Size and weight are big decision factors when you are trying to find the ideal camera for your needs.
In this section, we are going to illustrate the Sony TX66 and Sony NEX-5T side-by-side from the front, back and top in their relative dimensions. Sony TX66 has external dimensions of 93 x 54 x 13 mm (3.66 x 2.13 x 0.51″) and weighs 109 g (0.24 lb / 3.84 oz) (including batteries). Sony NEX-5T has external dimensions of 111 x 59 x 39 mm (4.36 x 2.31 x 1.53″) and weighs 276 g (0.61 lb / 9.74 oz) (including batteries).
Below you can see the front-view size comparison of the Sony TX66 and the Sony NEX-5T. Sony TX66 is clearly the smaller of the two cameras. Its body is 18mm narrower, 5mm shorter and 26mm thinner than Sony NEX-5T. As you can tell, actually this is not a fair size comparison since Sony TX66 has a built-in lens but Sony NEX-5T doesn't. Once you put a lens on NEX-5T, its thickness will increase significantly.
Now lets look at the top view comparison of Sony TX66 and Sony NEX-5T.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Sony TX66 is significantly lighter (167g ) than the Sony NEX-5T which may become a big advantage especially on long walking trips.
Again, this comparison may not be very useful in real life as we are comparing the weight of a camera with a built-in lens to the body-only weight of an interchangeable lens camera. Once you put a lens on NEX-5T, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Sony Cyber-shot DSC-TX66 nor Sony Alpha NEX-5T provides any type of weather sealing in their bodies, so you have to give extra care especially when you are shooting outdoors. If weather sealing is a must-have feature for you, check these sections: Top Compact Cameras with Weather Sealing Top Mirrorless Cameras with Weather Sealing
LCD Screen Size and Features
Sony TX66's 3.30" LCD screen is slightly larger than Sony NEX-5T's 3 screen.