The difference is in the set up.
The full squat is part of the clean deadlift, although the person takes the slack out of their body before the pull so the distinction of a clean deadlift from a conventional deadlift is more of splitting hairs than anything.
Your sticking point (or weak point) in the lift is usually dictated by the bar position relative to your feet when you start:
Bar closer to your shins means that the sticking point will be getting the bar off the floor, but if you can get it up you can lock it out.
Bar closer to your toes means the sticking point will be more towards lockout.
The recommended position if you are new to the exercise is bar over mid foot.
(This info from Paul Carter in his Strength-Life-Legacy eBook)
Double overhand or hook grip is good on warm-up sets, but eventually the bar will get too heavy for your grip with these.
That’s when you need to switch to a mixed grip.
Mixed grip stretches the bicep of the supinated hand (the hand facing away from you), so it is very important that you do not try to flex that bicep at all during the lift.
If you follow these steps you won’t have any problems:
- Take the slack out of your body (your arms full extended with no flex, your back starting to feel the barbell without actually pulling it off the floor).
- Keep the lumbar region rigid (lower back) during the lift. Some flex in the thoracic area (upper back) is OK and at heavy weights it is expected.
- Keep the head in a neutral position. Lifting it up or craning it side to side will leave you open to a neck strain.
- Push your heels through the floor.
- Lock out: knees, hips, and shoulders form a straight line through your ankles.
Deadlift is the ultimate posterior chain movement as far as muscle recruitment goes:
Lower back and abdominal muscles