Yes, they are the same period. This is evident in both the parallel usage made of these periods and in their mathematical equivalency.
Let's look first at the math, to make sure that this is clear.
A biblical year consisted of 12 months; and each month has 30 days. Therefore, a full year would be 360 days. Notably, in Hebrew, the word "yowm" often translated as "day" can also mean "time" or "year." The day-for-a-year principle, as given in both Numbers 14:34 and in Ezekiel 4:4-6, follows a very simple Hebrew play on words, using the dual meaning of "yowm" to establish the symbolic equivalence between a day and a prophetic year.
Prophetic Day-for-Year Time Formulae
After the number of the days in which ye searched the land, even forty
days, each day for a year, shall ye bear your iniquities, even forty
years, and ye shall know my breach of promise. (Numbers 14:34, KJV)
For I have laid upon thee the years of their iniquity, according to
the number of the days, three hundred and ninety days: so shalt thou
bear the iniquity of the house of Israel. And when thou hast
accomplished them, lie again on thy right side, and thou shalt bear
the iniquity of the house of Judah forty days: I have appointed thee
each day for a year. (Ezekiel 4:5-6, KJV)
The equivalencies, therefore, look like this:
- 1260 days / 360 days = 3 1/2 (3.5) years
- 3 1/2 (3.5) years = 42 months
- 42 months X 30 days = 1260 days
Whether we count in days, in months, or in years, each of these periods is the same. But we have one more equivalency to add: a "time." Again, because "yowm" can mean "day" or "time" or "year", the word "time," like "day," also represents a year. Because of this, one "time" is a year, "times," being plural, is two years, and half a time (or the dividing of time) is half a year.
Now let's look at how these time periods are used in Revelation.
And to the woman were given two wings of a great eagle, that she might
fly into the wilderness, into her place, where she is nourished for
a time, and times, and half a time, from the face of the serpent. (Revelation 12:14, KJV)
And the woman fled into the wilderness, where she hath a place
prepared of God, that they should feed her there a thousand two
hundred and threescore days. (Revelation 12:6, KJV)
And I will give power unto my two witnesses, and they shall prophesy
a thousand two hundred and threescore days, clothed in sackcloth. (Revelation 11:3, KJV)
NOTE: "Threescore" means three scores, a score being twenty; therefore, threescore = 60.
But the court which is without the temple leave out, and measure it
not; for it is given unto the Gentiles: and the holy city shall they
tread under foot forty and two months. (Revelation 11:2, KJV)
And there was given unto him a mouth speaking great things and
blasphemies; and power was given unto him to continue forty and two
months. (Revelation 13:5, KJV)
Notice that in Revelation 11:2, the time is given in months, but in the very next verse, it is repeated in days. This parallel usage shows clear equivalence. In 12:6, the time is again given in days, followed a few verses later (vs. 14) being given in times. Again, this is parallel usage.
Be careful: The 3 1/2 days of Revelation 11:9,11 also represent years, but three and a half years is clearly a different prophecy than one of 1260 years. So this is not an equivalent time period, nor is it referenced in parallel with the other prophecies in terms of its fulfillment.