We as humans are what place limits on things, people, and time. The Lord however, has no limits. None at all. Our Heavenly Father is always at work by way of the Holy Spirit.
But, the ‘word of God’ (Alma 23:3) does at times run into obstructions. In history there have been times where not everyone was able to read the word of God for themselves. There are also times and places where the word of God cannot be preached.
That’s the difference. While the Lord can be present, the word of God may not be. The two must work hand in hand to build new testimonies and to reinforce the ones already set in the hearts and minds of others.