אני חושבת שההבדל הכי חשוב הוא בשעות העבודה.

Because חושבת is the feminine singular form of to think in the present tense.

• אני חושבת = I think (said by a woman)
• אני חושב = I think (said by a man)

In Hebrew present tense, the verb often agrees with the speaker’s gender, even with אני (I).

שההבדל is made of two parts:

• ש־ = that
• ההבדל = the difference

So:

• שההבדל = that the difference

Hebrew often attaches short words like ש־ directly to the following word. So instead of writing them separately, they are joined together.

You may notice there are two ה letters in a row:

• ש + ההבדל → שההבדל

That is completely normal here.

Yes. הכי חשוב means most important.

Breakdown:

• חשוב = important
• הכי = most

So:

• חשוב = important
• הכי חשוב = most important

This is a very common way to form the superlative in modern Hebrew.

A more formal alternative is:

• החשוב ביותר = the most important

So both are possible, but הכי חשוב is very natural in everyday speech.

In this sentence, הוא works like is.

Hebrew does not usually use a present-tense verb meaning to be the way English does. Instead, in sentences like this one, Hebrew often uses a pronoun such as:

• הוא = he / it
• היא = she / it

Here it connects the two parts of the sentence:

• ההבדל הכי חשוב = the most important difference
• הוא בשעות העבודה = is in the working hours

So הוא is not really being translated as he here. It is functioning like a linking word, similar to is.

Because ב־ means in, at, or sometimes with regard to, depending on context.

So:

• שעות העבודה = the working hours / work hours
• בשעות העבודה = in the working hours / in the work hours

In this sentence, בשעות העבודה means something like:

• in the work hours
• in terms of the work hours
• when it comes to work hours

This kind of ב־ is very common in Hebrew when identifying the area where the difference exists.

This is a construct chain (called סמיכות in Hebrew), which is a very common Hebrew noun pattern.

• שעות = hours of ...
• העבודה = the work

Together:

• שעות העבודה = the hours of the work = the work hours / working hours

In Hebrew construct chains, the first noun usually does not take ה־ directly. The definiteness is often shown on the second noun:

• שעות עבודה = work hours / working hours
• שעות העבודה = the work hours / the working hours

So even though שעות does not have ה־, the whole phrase is definite because העבודה is definite.

Hebrew often uses a singular noun in construct phrases where English might use an adjective or a different structure.

• עבודה = work
• שעות העבודה = the hours of work = working hours / work hours

So Hebrew is not saying hours of works. It is using work as a category, just like English does in phrases such as:

• work hours
• office hours

This is completely natural Hebrew.

Only one word would need to change:

• אני חושבת שההבדל הכי חשוב הוא בשעות העבודה.
  spoken by a woman

• אני חושב שההבדל הכי חשוב הוא בשעות העבודה.
  spoken by a man

Everything else stays the same.

Yes, it is natural Hebrew.

The sentence structure is:

• אני חושבת = I think
• שההבדל הכי חשוב = that the most important difference
• הוא בשעות העבודה = is in the work hours

Hebrew often organizes information a little differently from English, especially with sentences using הוא/היא as a present-tense linker.

A very literal translation would sound like:

• I think that the most important difference is in the work hours.

That is normal Hebrew word order.

A common pronunciation is:

ani choshevet she-ha-hevdel hachi chashuv hu be-sha'ot ha-avoda

Word by word:

• אני = ani
• חושבת = choshevet
• שההבדל = she-ha-hevdel
• הכי = hachi
• חשוב = chashuv
• הוא = hu
• בשעות = be-sha'ot
• העבודה = ha-avoda

A few notes:

• ח is a throaty sound with no exact English equivalent.
• עבודה begins with ע, which in modern Israeli Hebrew is often very soft or almost silent in casual speech.
• The stress in העבודה is usually on the last syllable: avoDA.

Yes.

These are both correct:

• ההבדל הכי חשוב = the most important difference
• ההבדל החשוב ביותר = the most important difference

The difference is mostly style:

• הכי חשוב sounds very common and conversational
• החשוב ביותר sounds a bit more formal or written

In everyday speech, הכי חשוב is extremely common.